Kwabena Senyah

Perfect Asare

Jonathan Wilcox

Federica Angiolari

Riccardo Spezia

Dr Laurence A Angel
email: laurence.angel@tamuc.edu

Extending the competitive threshold collision-induced dissociation of Zn(II) ternary complexes using traveling-wave ion mobility-mass spectrometry

Keywords: threshold collision-induced dissociation, Synapt TCID, zinc ternary complexes, immobilized metal affinity chromatography, peptide tags, alternative metal binding peptide

The competitive threshold collision-induced dissociation (TCID) of the ternary complex [amb 5 +Zn(II)+NTA]  → [amb 5 +Zn(II)]  + NTA or → [NTA+Zn(II)]  + amb 5 , where amb 5 = His-Cys-Gly-Pro-Gly-Gly-Cys or Asp-His-Gly-Pro-Gly-Gly-Cys and NTA = nitrilotriacetic acid, were studied using traveling-wave ion mobility-mass spectrometry (TWIMMS). The analyses included calculating the reaction cross sections as a function of center-of-mass collision energy at three pressures of the argon collision gas, which covers the pressure range available in the TWIMMS instrument. The ternary complex contained one of the amb 5 peptides, whose His, Cys and/or Asp substituent groups could compete with the NTA carboxylate sites for binding Zn(II). A new molecular modeling procedure was developed, initially using PM6 geometry-optimizations and thermochemical analyses to locate lowenergy conformers of the ternary complex and its products that also had collision cross sections ( Ω He ), measured using the ion size scaled Lennard-Jones (L-J) method, that were close to the TWIMMS measured Ω He . A selection of these conformers were further geometry-optimized at the DFTB/3OB_D4 level of theory and using these as starting structures, molecular dynamics (MD) simulations were conducted to sample the ensemble of structures L-J Ω He at 300 K. From these analyses, a selection of reactant and product conformers whose L-J Ω He best matched the TWIMMS Ω He were used in the TCID fitting of the center-of-mass energy-dependent, reaction cross sections extrapolated to zero pressure.

The TCID fitting determined the threshold energies of the two product channels which in the absence of an activation barrier in excess of the energy of the products equates to the 0 K dissociation enthalpies (H 0 ). The difference in H 0 for the two competing reactions allowed for a relative gasphase Zn(II) affinity scale to be constructed for the amb 5 peptides studied here and from our previous published amb 5 research.

Introduction

The competitive threshold collision-induced dissociation (TCID) method, developed by Armentrout, Ervin and Rodgers, 1-3 is a reaction dynamics method for obtaining the thermochemistry of competing reactions driven by the collision between the reactant and an inert collision gas, and is applied through the CRUNCH program. [START_REF] Armentrout | CRUNCH, Fortran program[END_REF] The competitive TCID method has been applied to a variety of chemical systems including ionic liquid clusters, [START_REF] Roy | 1-Alkyl-3-methylimidazolium cation binding preferences in hexafluorophosphate ionic liquid clusters determined using competitive TCID measurements and theoretical calculations[END_REF][START_REF] Roy | Absolute Trends and Accurate and Precise Gas-Phase Binding Energies of 1-Alkyl-3-Methylimidazolium Tetrafluoroborate Ionic Liquid Clusters from Combined Independent and Competitive TCID Measurements[END_REF] protonated tripeptides, [START_REF] Mookherjee | Thermodynamics and Reaction Mechanisms for Decomposition of a Simple Protonated Tripeptide, H + GAG: a Guided Ion Beam and Computational Study[END_REF][START_REF] Mookherjee | Thermodynamics and Reaction Mechanisms of Decomposition of the Simplest Protonated Tripeptide, Triglycine: A Guided Ion Beam and Computational Study[END_REF] sodium cation complexes, [START_REF] Amicangelo | Relative and absolute bond dissociation energies of sodium cation complexes determined using competitive collision-induced dissociation experiments[END_REF] and the gasphase proton affinities organic molecules. [START_REF] Chen | Re-Evaluation of the Proton Affinity of 18-Crown-6 Using Competitive Threshold Collision-Induced Dissociation Techniques[END_REF][START_REF] Jia | Threshold Collision-Induced Dissociation of Hydrogen-Bonded Dimers of Carboxylic Acids[END_REF][START_REF] Angel | Gas-phase acidities and O-H bond dissociation enthalpies of phenol, 3-methylphenol, 2,4,6-trimethylphenol, and ethanoic acid[END_REF][START_REF] Amicangelo | Re-Evaluation of the Proton Affinity of 18-Crown-6 Using Competitive Threshold Collision-Induced Dissociation Techniques[END_REF][START_REF] Deturi | Competitive Threshold Collision-Induced Dissociation: Gas-Phase Acidities and Bond Dissociation Energies for a Series of Alcohols[END_REF] Recently we have shown a competitive TCID approach for studying a series of alternative metal binding (amb) peptides, which was applied to the competitive dissociation of the [amb+Zn(II)+NTA]  ternary complex: [START_REF] Flores | Thermochemical and conformational studies of Ni(II) and Zn(II) ternary complexes of alternative metal binding peptides with nitrilotriacetic acid[END_REF][START_REF] Corrales | Thermochemical Studies of Ni(II) and Zn(II) Ternary Complexes using Ion Mobility-Mass Spectrometry[END_REF] an original application due to the ternary complexes relatively large size and the use of the traveling-wave ion mobility-mass spectrometry (TWIMMS) platform. [START_REF] Pringle | An investigation of the mobility separation of some peptide and protein ions using a new hybrid quadrupole/travelling wave IMS/oa-ToF instrument[END_REF] The research presented here further extends the TCID instrumental and theoretical approaches applied to the TWIMMS platform and provides the thermochemistry and relative Zn(II) affinity for two new amb 5 species (Fig 1 ) and compares them with our previous results. This new TCID research, includes converting ion intensities into product reaction cross sections ( p ) which are extrapolated to the single collision limit, and the application of a new theoretical approach for selecting the reactant and product conformers to use in the TCID modeling. Notably, we have used theoretical calculations to identify the structures of the ions by comparing theoretical with experimental collision cross sections. This was done in two ways: (i) using the structures resulting from geometry optimization;

(ii) using an ensemble of structures sampled by molecular dynamics simulations. The first approach is what is typically done, while the second one was much less used. Typically classical molecular dynamics (MD) simulations were done in the past improve the collision cross sections of large macromolecules, [START_REF] Tao | The contributions of molecular framework to IMS collision cross-sections of gas-phase peptide ions[END_REF][START_REF] Lim | Application of molecular dynamics simulation to improve the theoretical prediction for collisional cross section of aromatic compounds with long alkyl chains in crude oils[END_REF] while here we used first-principles MD simulations using tight-binding Density Functional Theory in order to correctly consider the Zn(II) binding and allowing possible proton transfers.

Our previous research of the amb peptides showed that by preparing their samples in a series of acidic to basic pH solutions that pH-dependent metal binding was observed and by changing residues in their primary structure the specificity for chelating different metal ions could be adapted. [START_REF] Sesham | The pH dependent Cu(II) and Zn(II) binding behavior of an analog methanobactin peptide[END_REF][START_REF] Choi | Redox activity and multiple copper(I) coordination of 2His-2Cys oligopeptide[END_REF][START_REF] Wagoner | The multiple conformational charge states of zinc(II) coordination by 2His-2Cys oligopeptide investigated by ion mobility -mass spectrometry, density functional theory and theoretical collision cross sections[END_REF][START_REF] Vytla | Applying Ion Mobility-Mass Spectrometry Techniques for Explicitly Identifying the Products of Cu(II) Reactions of 2His-2Cys Motif Peptides[END_REF][START_REF] Lin | Weak acid-base interactions of histidine and cysteine affect the charge states, tertiary structure, and Zn(II)-binding of heptapeptides[END_REF][START_REF] Yousef | Ion mobility-mass spectrometry techniques for determining the structure and mechanisms of metal ion recognition and redox activity of metal binding oligopeptides[END_REF][START_REF] Yousef | Comparison of the pH-dependent formation of His and Cys heptapeptide complexes of nickel(II), copper(II), and zinc(II) as determined by ion mobility-mass spectrometry[END_REF][START_REF] Ilesanmi | pH dependent chelation study of Zn(II) and Ni(II) by a series of hexapeptides using electrospray ionization -Ion mobility -Mass spectrometry[END_REF][START_REF] Flores | Formation of Co(II), Ni(II), Zn(II) complexes of alternative metal binding heptapeptides and nitrilotriacetic acid: Discovering new potential affinity tags[END_REF][START_REF] Vangala | ESI-IM-MS reveals the metal binding of three analog methanobactin peptides with different numbers of free Cys at physiological pH[END_REF] Some of the most extensive metal binding research was on a series of amb 5 heptapeptides, [START_REF] Flores | Thermochemical and conformational studies of Ni(II) and Zn(II) ternary complexes of alternative metal binding peptides with nitrilotriacetic acid[END_REF][START_REF] Corrales | Thermochemical Studies of Ni(II) and Zn(II) Ternary Complexes using Ion Mobility-Mass Spectrometry[END_REF][START_REF] Wagoner | The multiple conformational charge states of zinc(II) coordination by 2His-2Cys oligopeptide investigated by ion mobility -mass spectrometry, density functional theory and theoretical collision cross sections[END_REF][START_REF] Lin | Weak acid-base interactions of histidine and cysteine affect the charge states, tertiary structure, and Zn(II)-binding of heptapeptides[END_REF][START_REF] Yousef | Comparison of the pH-dependent formation of His and Cys heptapeptide complexes of nickel(II), copper(II), and zinc(II) as determined by ion mobility-mass spectrometry[END_REF][START_REF] Flores | Formation of Co(II), Ni(II), Zn(II) complexes of alternative metal binding heptapeptides and nitrilotriacetic acid: Discovering new potential affinity tags[END_REF] named in alphabetical order amb 5A to amb 5R , which were designed to explore the primary structure acetyl-Aa 1 -Aa 2 -Gly 3 -Pro 4 -Tyr 5 -Aa 6 -Aa 7 , where the Aa were different combinations of His, Cys or Asp that have metal binding substituent groups. The central residues provided a spacer, a hinge, and -metal ion interaction.

However, the previous Zn(II) binding studies indicated that it was the substituent group in the Aa 1 -Aa 2 -Aa 7 positions with the carboxylate at the terminus that provided the distorted tetrahedral Zn(II) coordination. [START_REF] Lin | Weak acid-base interactions of histidine and cysteine affect the charge states, tertiary structure, and Zn(II)-binding of heptapeptides[END_REF][START_REF] Ilesanmi | pH dependent chelation study of Zn(II) and Ni(II) by a series of hexapeptides using electrospray ionization -Ion mobility -Mass spectrometry[END_REF] Here we extend this series with simplified primary structures for amb 5S and amb 5T (Fig 1)

which have alternative Aa 1 -Aa 2 -Aa 7 binding sites for forming the binary[amb 5 +Zn(II)]  and ternary [amb 5 +Zn(II)+NTA]  complexes but replace the sites at Tyr 5 -Aa 6 with Gly 5 -Gly 6 , which will test whether the Tyr 5 -zinc ion interaction or the Aa 6 substituent sites were significant in our previous Zn(II) binding

Experimental, computational and molecular modeling methods

Reagents and preparation of the ternary complexes

The peptides ac-His-Cys-Gly-Pro-Gly-Gly-Cys (amb 5S ) and ac-Asp-His-Gly-Pro-Gly-Gly-Cys (amb 5T ) were synthesized by PepmicCo (http://www.pepmic.com/). Zinc(II) nitrate hexahydrate (99%+ purity) was acquired from Alfa Aesar (www.alfa.com/). Ammonium hydroxide (trace metal grade) and ammonium acetate (ultrapure) were acquired from Fisher Scientific (http://www.Fishersci.com/) and VWR (https://us.vwr.com/), respectively. Stock and working solutions were made with deionized water >17.8 M cm (http://www.millipore.com) and HPLC grade methanol (http://www.Fishersci.com/). The [amb 5 +Zn(II)+NTA] -complex was prepared by combining the zinc nitrate hexahydrate with the NTA followed by the addition of the amb 5 and then 50% methanol in DI water. Further dilution with DI water produced samples with final concentrations of 25.0 µM amb 5 or Zn(II) and 50.0 µM NTA in 10% methanol aqueous solution. The solutions were thoroughly mixed and left at room temperature for 10 minutes. The final solutions had a pH 2.8-3.0.

Threshold collision-induced dissociation of the ternary complex

The instrumental analyses were conducted using the Waters Synapt G1 instrument 17 (Fig S1 )   using operating conditions as described in the Supporting Information. The negatively-charged [amb 5 +Zn(II)+NTA]  complex was resolved by the transmission quadrupole, collected in the trap and injected with a 200 s gate into the ion mobility traveling-wave (IM T-wave) cell. The [amb 5 +Zn(II) +NTA]  ions underwent about 10,000 collisions with the nitrogen buffer gas before acceleration into the transfer T-wave cell using predetermined collision energies (CE). The dissociation of the complex in the transfer T-wave meant the product ions had the same arrival time distribution (ATD) as the precursor [amb 5 +Zn(II)+NTA]  complex, and only those were included in the analyses. [START_REF] Flores | Thermochemical and conformational studies of Ni(II) and Zn(II) ternary complexes of alternative metal binding peptides with nitrilotriacetic acid[END_REF][START_REF] Corrales | Thermochemical Studies of Ni(II) and Zn(II) Ternary Complexes using Ion Mobility-Mass Spectrometry[END_REF] The ternary complex and product ions were identified using the TOF mass analyzer operated in V-mode by their m/z isotope patterns. Analyses of the data was conducted using the Driftscope 2.0 and MassLynx 4.1 softwares. The ATDs were extracted from the Driftscope 2.0 software and the area under each of the ATDs were integrated to determine the relative intensities of the precursor and products ions. The procedure was repeated for a series of transfer CE that included the range that covered the 0-100% dissociation of the [amb 5 +Zn(II)+NTA]  . Moreover, each series of CE were repeated using three argon collision gas pressures, covering the upper and lower pressure range available from the Synapt G1 instrument.

Collision cross sections

In separate experiments, with the quadrupole in non-resolving mode and no transfer CE, the collision cross sections (CCS) of the [amb 5 +Zn(II)+NTA]  and [amb 5 +Zn(II)]  complexes were measured using D-L polyalanine calibrants to make a calibration curve to convert the ATDs of the amb 5 complexes into CCS as measured in helium buffer gas (Ω He ). The measurement of Ω He allowed the comparison of the TWIMMS measured Ω He with the geometry-optimized conformations found by the molecular modeling, where their Ω He were calculated by the Lennard-Jones (L-J) ion size scaled method using the Sigma program. [START_REF] Wyttenbach | Effect of the long-range potential on ion mobility measurements[END_REF] Details of these methods are described in the Supporting Information.

Molecular modeling of [amb 5 +Zn(II)+NTA] -conformers and their products

An initial study for locating a series of geometry-optimized conformers of the negatively charged [amb 5 +Zn(II)+NTA]  complexes and their products was conducted using the semi-empirical PM6 method [START_REF] Stewart | Optimization of parameters for semiempirical methods V: Modification of NDDO approximations and application to 70 elements[END_REF] from Gaussian09, 32 using starting structures with structural modifications to test which combination of the His, Cys or Asp substituent groups and the NTA carboxyl groups would optimize to give the lowest-energy conformers that also had L-J Ω He (measured with an average of 200 measurements using the Sigma program with an accuracy set at 0.5%) that were close to the experimental TWIMMS Ω He .

From these initial results, a selection of conformers that exhibited these criteria but had different binding configurations were further geometry-optimized using tight-binding Density Functional Theory (DFTB) using the 3OB Slater-Koster parameters with third order corrections [START_REF] Gaus | Parametrization and Benchmark of DFTB3 for Organic Molecules[END_REF][START_REF] Gaus | Parameterization of DFTB3/3OB for Sulfur and Phosphorus for Chemical and Biological Applications[END_REF][START_REF] Lu | Parametrization of DFTB3/3OB for Magnesium and Zinc for Chemical and Biological Applications[END_REF] and D4 dispersion corrections [START_REF] Caldeweyher | Extension of the D3 dispersion coefficient model[END_REF][START_REF] Caldeweyher | A generally applicable atomic-charge dependent London dispersion correction[END_REF] (hereafter called 3OB_D4), their L-J Ω He were measured before molecular dynamics (MD) simulations were conducted using these DFTB/3OB_D4 conformers (5 ps equilibrium and 20-50 ps dynamics with L-J Ω He set to 0.5 % to do a single calculation for each structure extracted from MD simulations) to obtain the distribution and average L-J Ω He of the conformer at 300 K. In this way, the standard deviation obtained from multiple estimations of L-J Ω He of one structure is smaller than the standard deviation on L-J Ω He obtained from a conformational sampling. The temperature was controlled by a Langevin thermostat with a friction coefficient of 0.01 fs -1 (in the equilibration portion a higher friction coefficient, 0.1 fs -1 , was used) and an integration time step of 1 fs was used. Simulations were done using our in-house code [START_REF] Angiolari | Quantum versus Classical Unimolecular Fragmentation Rate Constants and Activation Energies at Finite Temperature from Direct Dynamics Simulations[END_REF] which uses the integration scheme proposed by Ceriotti et al. [START_REF] Ceriotti | Efficient stochastic thermostatting of path integral molecular dynamics[END_REF] enabling us to include nuclear quantum effects via the Ring Polymer Molecular Dynamics method [START_REF] Craig | Quantum statistics and classical mechanics: Real time correlation functions from ring polymer molecular dynamics[END_REF] with a mild thermostat on the beads, while a classical trajectory is recovered when the number of beads (P) is set to 1. Here we used P=1 for all the trajectories except for one case in which P=8 was also used. The dynamics routine is coupled with DFTB+ software to obtain energies and gradients. [START_REF] Hourahine | DFTB+, a software package for efficient approximate density functional theory based atomistic simulations[END_REF]

Center-of-mass collision energy and product reaction cross sections

The lab-frame collision energy (E lab ) applied to the transfer cell was converted to center-of-mass collision energy E cm using the average mass of the argon (m Ar ) collision gas and the average mass of the [amb 5 +Zn(II)+NTA]  ternary complex (m TC ) by equation 1.

E cm = E lab m Ar /(m Ar + m TC ) (1)
where E cm is the average energy converted from the collision into internal energy of the ternary complex and available for the dissociation reaction. The E cm -dependent intensities of the product ions are converted to reaction cross sections using Beer's law from the total (I 0 ) and transmitted (I) reactant ion intensities 42

I = I 0 exp(- tot nl) (2)
where  tot is the total reaction cross section, n is the argon gas density, l is the path length of the transfer collision cell (10.0 cm) and I 0 is determined from

I 0 = I + I p (3)
and includes the sum of the two product ion intensities I p produced by the reactions. The individual product reaction cross sections ( p ) are given by  p =  tot (I P /I P ) (4)

CRUNCH analyses using the competitive threshold collision induced dissociation method

The competitive TCID model for simultaneously fitting the two competing E cm -dependent product reaction cross sections [START_REF] Armentrout | Statistical Rate Theory and Kinetic Energy-Resolved Ion Chemistry: Theory and Applications[END_REF][START_REF] Rodgers | Statistical modeling of competitive threshold collision-induced dissociation[END_REF] was applied via the CRUNCH program. [START_REF] Armentrout | CRUNCH, Fortran program[END_REF] The TCID model includes (1) internal energy distribution of the [amb 5 +Zn(II)+NTA]  complex, [START_REF] Dalleska | Solvation of Transition Metal Ions by Water. Sequential Binding Energies of M + (H 2 O)x (x = 1-4) for M = Ti to Cu Determined by Collision-Induced Dissociation[END_REF] (2) convolution over translational energy distributions of the collision between [amb 5 +Zn(II)+NTA]  and the Ar collision gas, [START_REF] Ervin | Translational energy dependence of Ar + + XY → ArX + + Y (XY = H 2 , D 2 , HD) from thermal to 30 eV c.m[END_REF] (3) statistical RRKM rate constants into the two product channels and correction of the kinetic shifts due to the 50 s time window from the collision cell to the TOF detector, 3 and (4) integration over the total rotational angular momentum J levels. [START_REF] Deturi | Competitive Threshold Collision-Induced Dissociation: Gas-Phase Acidities and Bond Dissociation Energies for a Series of Alcohols[END_REF][START_REF] Iceman | Collision-induced dissociation and theoretical studies of K + complexes with ammonia: a test of theory for potassium ions[END_REF] The probability of dissociation and detection of the energized ternary complex with total energy E* to product channel j is given by first-order reaction kinetics of two product channels using equation 5.

P D,j (E*,J) = k j (E*,J) / k tot. (E*,J) [1 -exp(-k tot. (E*,J))τ] (5)
where k tot. = Σk j is the total dissociation rate constant of the individual channels j and τ is the time-of-flight of the center-of-mass of the system from the collision cell to the mass spectrometer detector. 2,3 J is the angular momentum quantum number for the rotational energies of the energized molecule and orbiting transition-state configuration. The long-range potential, using molecular polarizabilities and dipole moments of the neutral species, describes the ion-induced-dipole interaction as a locked dipole. [START_REF] Iceman | Collision-induced dissociation and theoretical studies of K + complexes with ammonia: a test of theory for potassium ions[END_REF] These analyses require vibrational and rotational frequencies for the reactant and products and the polarizabilities and dipole moments for the neutral products taken from the PM6 or DFTB calculations or the NIST database.

The complete evaluation of the energies available for the dissociation of the ternary complex into the two product channels allows for the thermochemical analyses of these reactions. Over the higher E cm = 0.6-2.4 eV CE range, the  p exhibited an increase as argon gas pressures decreased, resulting in the overall increase in  p from the polynomial extrapolation (Fig 2b). This increase in reactivity may be explained because the initial collision of the accelerated ternary complex with an argon atom is most precisely controlled by the applied transfer collision energy when the ternary complex has an initial collision-free path that allows it to accelerate to the applied transfer collision energy before the initial collision. However, if there are multiple collisions along this initial path then these generally are less energetic because the complex does not have enough time between collisions to accelerate to the full applied collision energy. Subsequently these lower energy multiple collisions can result with less internal excitation of the ternary complex. Moreover, lower energy multiple collisions inside the transfer T-wave cell can result with some of the initial internal excitation energy from the initial collision being removed, resulting in partial deactivation of the ternary complex, both these mechanisms will be most pronounced at the higher argon gas pressures. Therefore, the linear extrapolation of the  p using the three pressures to the single-collision limit (Fig 3d)

Results and Discussion

The collision gas pressure dependence on the products reaction cross sections

increased the  p over the whole E cm = 0.6-2.4 eV region and produced well-defined threshold regions for all three product ions.

Conformers of [amb 5 +Zn(II)+NTA]  complexes and the dissociation products

A new theoretical approach was used to locate the conformers of [amb 5 +Zn(II)+NTA] -and their dissociation products [amb 5 +Zn(II)]  + NTA and [NTA+Zn(II)]  + amb 5 to use in the TCID modeling of these reactions. The semi-empirical PM6 method was used to explore a wide range of conformers of the reactants and products, where the peptide bonds for the amb 5 species were kept in their trans configurations [START_REF] Wagoner | The multiple conformational charge states of zinc(II) coordination by 2His-2Cys oligopeptide investigated by ion mobility -mass spectrometry, density functional theory and theoretical collision cross sections[END_REF] with different arrangements of the potential binding sites of His, Cys, Asp and the carboxyl groups. Table 1 shows the L-J Ω He of a selection of different Zn(II) binding motifs located by PM6 that exhibited the lowest-energy thermochemical analyses and L-J Ω He close to the Ω He measured by TWIMMS. These conformers were further geometry-optimized at DFTB/3OB_D4 level of theory and their L-J Ω He measured to compare to the TWIMMS Ω He . Using the DFTB/3OB_D4 geometry-optimized conformers as starting geometry, MD simulations were conducted at 300 K and 500 conformers were extracted over the 50 ps time-frame of the simulations to measure their distributions and average L-J Ω He and locate which of the conformers compared best with the TWIMMS Ω He and select those to use in the TCID modeling. obtained from the corresponding optimized geometries. For the amb 5T peptide using the S7a initial geometry, we have run simulations including nuclear quantum effects and the calculated Ω He = 174 ± 4 Å 2 was slightly larger than the classical one, but inside the statistical uncertainty. Since these calculations are much more computationally expensive and the difference is not so important for all the other systems we consider here only the Newtonian trajectories.

The sampling of the ensemble structures from the MD simulations allowed the L-J Ω He distributions of the conformers of [amb 5 +Zn(II)+NTA] -and [amb 5 +Zn(II)]  (shown in bold in Table 1) to be compared with the TWIMMS Ω He distributions (Fig 4). Figure 4a given thermodynamics conditions should include the contribution of multiple conformers, however the limitation in simulation time-length due to computational reasons is typically at the origin of an insufficient sampling. To contour this problem, we have run trajectories using as initial geometries different conformers, calculate the respective Ω He and associated distributions and summed them. Figure 5 shows the comparison of the TWIMMS Ω He distribution of the [amb 5S +Zn(II)+NTA] -complex with the L-J Ω He distributions from the MD simulations using as starting geometries the three DFTB/3OB_D4 conformers S2a, S2b, and S2c (Table 1). If the abundances of the conformers S2a and b are 55% relative to the 100% conformer S2c then a reasonably good reproduction of the TWIMMS Ω He distribution would be obtained with the summation of all three of these L-J Ω He distributions, indicating these three conformers could be present in the experiment. The following TCID analyses will use the DFTB/3OB_D4 conformers selected in bold from Table 1, and in the Supporting Information a selection of the PM6 conformers from Table 1 will be used to ascertain how these different conformer's vibrational frequencies affect the final TCID threshold analyses.

Evaluation of the TCID thermochemical analysis

The difference in the 0 K changes in enthalpies for the two competing reactions 6 and 7, i.e.,

 Zn H 0 = H 0 (6) -H 0 (7) =  Zn H 0 (amb 5 ) - Zn H 0 (NTA), is a more consistent measurement than the two absolute H 0 values, because many of the uncertainties in the TCID measurement cancel out. [START_REF] Angel | Gas-phase acidities and O-H bond dissociation enthalpies of phenol, 3-methylphenol, 2,4,6-trimethylphenol, and ethanoic acid[END_REF][START_REF] Ervin | Experimental Techniques in Gas-Phase Ion Thermochemistry[END_REF] The  Zn H 0 also provides a relative gas-phase Zn(II) affinity scale for the amb 5 species studied here and in our previous TCID research based on reactions 6 and 7. [START_REF] Corrales | Thermochemical Studies of Ni(II) and Zn(II) Ternary Complexes using Ion Mobility-Mass Spectrometry[END_REF] Table 2 shows a comparison of the relative  Zn H 0 using NTA as the baseline and includes the previously studied amb 5A and amb 5H , which have the common primary structure ac-Aa 1 -Cys 2 -Gly 3 -Pro 4 -Tyr 5 -His 6 -Cys 7 , where the amino acid Aa 1 = His 1 or Asp 1 , respectively, with amb 5A exhibiting a more exothermic Zn(II) affinity than amb 5H. . The primary structure of amb 5A is also closely related to the new amb 5S studied here where their primary structures only differ by the Tyr 5 -His 6 residues being replaced by Gly 5 -Gly 6 , respectively. This allows the determination of how the substituent groups of Tyr 5 -His 6 effect the Zn(II) affinity of these two amb 5 peptides. Table 2 shows the  Zn H 0 measurement for amb 5S using the DFTB conformers (Fig 6) with the two  Zn H 0 measurements made using the PM6 conformers, with the conformers and TCID fits shown in the Supporting Information (Fig S8, S9 and S11). The range of these three  Zn H 0 measurements is 0.11 eV, but all three values are twofold or more exothermic than the  Zn H 0 of amb 5A , previously modeled with PM6 conformers. [START_REF] Corrales | Thermochemical Studies of Ni(II) and Zn(II) Ternary Complexes using Ion Mobility-Mass Spectrometry[END_REF] These results clearly indicate that the amb 5A substituent groups of Tyr 5 -His 6 decrease the Zn(II) affinity in respect to the amb 5S . The Tyr residue was originally included in the primary structure of the amb peptides because its substituent group could provide a stabilizing  -zinc cation interaction and spectroscopic tag for absorbance and fluorescence studies. [START_REF] Choi | Redox activity and multiple copper(I) coordination of 2His-2Cys oligopeptide[END_REF][START_REF] Vangala | ESI-IM-MS reveals the metal binding of three analog methanobactin peptides with different numbers of free Cys at physiological pH[END_REF] However, the results here suggests that steric effects from the bulky Tyr side group are detrimental to Zn(II) binding at least for these amb 5 peptides. The loss of Zn(II) affinity from the imidazole of His 6 indicates that the imidazole does not provide a Zn(II) binding site. This is consistent with our previous amb research that showed the Zn(II) binding sites are the substituent groups in the first two positons, e.g., His 1 -Cys 2 , and the combination of the thiolate of Cys in the last position with the carboxylate terminus that provided the four coordination sites for the distorted tetrahedral geometry. [START_REF] Lin | Weak acid-base interactions of histidine and cysteine affect the charge states, tertiary structure, and Zn(II)-binding of heptapeptides[END_REF][START_REF] Ilesanmi | pH dependent chelation study of Zn(II) and Ni(II) by a series of hexapeptides using electrospray ionization -Ion mobility -Mass spectrometry[END_REF] The  Zn H 0 measurements of amb 5S are also more exothermic than the  Zn H 0 measurements of amb 5T , which used the DFTB conformers ( to the dissociation of two [amb 5 +Zn(II)+NTA] -ternary complexes contining either amb 5S and amb 5T using the CRUNCH reaction dynamics program. [START_REF] Armentrout | CRUNCH, Fortran program[END_REF] The amb 5S and amb 5T had simplified primary structures to those studied previously to test whether the Zn(II) affinity were affected by replacing Tyr 5 -His 6 with Gly 5 -Gly 6 from the amb 5 structure. [START_REF] Lin | Weak acid-base interactions of histidine and cysteine affect the charge states, tertiary structure, and Zn(II)-binding of heptapeptides[END_REF][START_REF] Ilesanmi | pH dependent chelation study of Zn(II) and Ni(II) by a series of hexapeptides using electrospray ionization -Ion mobility -Mass spectrometry[END_REF] The analyses included converting ion intensities into product reaction cross sections which are extrapolated to the single collision limit, and the application of a new theoretical approach for selecting the reactant and product conformers to use in the TCID modeling. The competitive TCID analyses required the vibrational and rotational frequencies for the ternary complex and their dissociation products, including polarizabilities and dipole moments of the neutral products. This new method included theoretical calculations to identify the structures of the ions by comparing theoretical with experimental collision cross sections by (i) identifying conformers from PM6 geometry optimization and frequency calculations; (ii) using an ensemble of structures sampled by molecular dynamics simulations using tight-binding Density Functional Theory.

The TCID analyses included using alternative sets of conformers to test their effect on the dissociation reactionsH 0 and the amb 5 relative gas-phase Zn(II) affinities. The maximum range of Zn(II) affinities was 0.11 eV using three sets of alternative sets conformers and was consistent enough to be able to determine differences in the relative Zn(II) affinities of the two amb 5 species studied here and two from our previous competitive TCID analyses. The results revealed that the substituent groups of Tyr 5 -His 6 decreased the Zn(II) affinity. For Tyr 5 the potential of providing a second-shell stabilizing  -zinc cation interaction seems to be out-weighed by steric effects interfering with the first-shell Zn(II) coordination. The loss of Zn(II) affinity from imidazole of His 6 also indicated that this imidazole does not bind in the first shell to the Zn(II), consistent with our previous research [START_REF] Lin | Weak acid-base interactions of histidine and cysteine affect the charge states, tertiary structure, and Zn(II)-binding of heptapeptides[END_REF][START_REF] Ilesanmi | pH dependent chelation study of Zn(II) and Ni(II) by a series of hexapeptides using electrospray ionization -Ion mobility -Mass spectrometry[END_REF] indicating the Zn(II) binding sites are either the His, Cys, or Asp in the first two positions of the primary structure and the combination of the thiolate of Cys 7 and its carboxylate terminus binding the Zn(II) in a distorted tetrahedral coordination geometry.

studies

  The overall 1 charge state of the complexes are determined by the oxidation state of Zn(II) and the protonation states of the weak acid or basic sites of the amb 5 and/or NTA, relating to 3 negativelycharged sites, i.e., [amb 5 H+Zn(II)+NTA-2H]  , [amb3H+Zn(II)]  or [NTA3H+Zn(II)]  . In the following script, the '3H' is omitted from the names of the complexes, but the descriptions of the molecular modeling results include a discussion of the protonation states in these complexes.

Figure 1 .

 1 Figure 1. The primary structures of the alternative metal binding amb 5S and amb 5T peptides with the potential metal-binding of the substituent groups of His, Cys or Asp in the first, second and last positons shown in green, blue and brown.

Figure

  Figure2ashows the two product reaction cross sections ( p ) for [amb 5S +Zn(II)]  and [NTA+Zn(II)]  that were produced by the TCID of [amb 5S +Zn(II)+NTA]  taken at three argon gas pressures and the polynomial extrapolation of the  p using the three gas pressures to the single collision limit (Fig2b). The  p of [amb 5S +Zn(II)]  (Fig2a) over the lowest E cm = 0.2-0.6 eV, exhibited elevated  p that were directly dependent on the pressure of the argon gas, a feature not observed in our previous TCID studies.[START_REF] Flores | Thermochemical and conformational studies of Ni(II) and Zn(II) ternary complexes of alternative metal binding peptides with nitrilotriacetic acid[END_REF][START_REF] Corrales | Thermochemical Studies of Ni(II) and Zn(II) Ternary Complexes using Ion Mobility-Mass Spectrometry[END_REF] A polynomial extrapolation of the  p to the zero argon pressure limit, removed this feature (Fig2b) and produced well-defined threshold regions for the [amb 5S +Zn(II)]  and [NTA+Zn(II)]   product channels.

Figure 2 .

 2 Figure 2. The threshold collision-induced dissociation of [amb 5S +Zn(II)+NTA]  showing a) the reaction cross sections for the product channels [amb 5S +Zn(II)]  and [NTA+Zn(II)]  taken at argon gas pressures of 0.0691 mbar, 0.0290 mbar, and 0.0171 mbar, and b) the polynomial extrapolation of the reaction cross sections to zero argon gas pressure at the single collision limit.

Figure 3 .

 3 Figure 3. The threshold collision-induced dissociation of [amb 5T +Zn(II)+NTA]  showing the reaction cross sections for the product channels of [amb 5T +Zn(II)]  , [NTA+Zn(II)]  and [amb 5T -H 2 O+Zn(II)]  at collision gas pressures of a) 0.0683 mbar argon, b) 0.0288 mbar argon, c) 0.0164 mbar argon in the transfer collision cell,and d) the linear extrapolation of the reaction cross section to zero argon gas pressure at the single collision limit.

Figure 3

 3 Figure3shows the  p versus E cm from the TCID of [amb 5T +Zn(II)+NTA]  producing the [amb 5T +Zn(II)]  , [NTA+Zn(II)]  and [amb 5T -H 2 O+Zn(II)]  channels, the last channel being the sequential dissociation of [amb 5T +Zn(II)]  through the loss of a water molecule from amb 5T . The results from the three different argon gas pressures in the transfer collision cell (Fig3a, b, and c) show the  p exhibit a systematic increase as the argon gas pressure decreased over 0.0683 mbar, 0.0288 mbar to 0.0164 mbar, indicating fewer collisions increased the reactivity of the activated complex (see discussion above).

  compares the amb 5S complexes, which show the TWIMMS and MD exhibit distributions centered around the average Ω He , but with the MD distributions significantly narrower, exhibiting FWHM = 6 Å 2 and FWHM = 4 Å 2 compared to the TWIMMS FWHM = 12 Å 2 and FWHM = 15 Å 2 for [amb 5S +Zn(II)+NTA] -and [amb 5S +Zn(II)]  , respectively. A comparison of the amb 5T complexes also show narrower MD Ω He distributions, FWHM = 5 Å 2 and FWHM = 4 Å 2 compared to the TWIMMS FWHM = 14 Å 2 and FWHM = 13 Å 2 for [amb 5T +Zn(II)+NTA] -and [amb 5T +Zn(II)]  , respectively. The MD Ω He distributions are the changes in structural size of the complex isolated in an "implicit" bath by defining a 300 K temperature using the Langevin equations. For the TWIMMS Ω He measurement there are additional broadening affects that includes the initial 200 s injection time of the ions into the IM T-wave cell, followed by deflections of the ions into slightly different trajectories by collisions with the N 2 buffer gas as they are pushed through the IM T-wave cell by the traveling waves. The T-wave heights and velocities in this study kept the time distribution minimal, e.g., for [amb 5S +Zn(II)+NTA]  the final time distribution was FWHM = 800 s.

Figure 4 .

 4 Figure 4. The comparison of the TWIMMS collision cross section distributions of the [amb 5 +Zn(II) +NTA] -complexes and their products [amb 5 +Zn(II)] -with the collision cross section distributions from the molecular dynamics (MD) simulations of the DFTB/3OB_D4 conformers. Another contribution to the broader TWIMMS Ω He distributions could be the average temperature of the complexes in the IM T-wave cell being on average hotter than the 300 K used in the MD simulations. A previous study 46 of the temperature of peptide ions in the IM T-wave cell of the G2 Synapt instrument indicated that the initial injection resulted in collisions with the nitrogen buffer gas that internally excited the peptide ions to 449 K, before they passed down the IM T-wave cell and the

Figure 5 .

 5 Figure 5. The comparison of the TWIMMS collision cross section distribution of the [amb 5S +Zn(II) +NTA] -complex with the collision cross section distributions from the molecular dynamics simulations of the three conformers S2a, S2b, and S2c geometry-optimized by DFTB/3OB_D4. The relative abundances of conformers S2a = b = 55% and conformer c = 100%.

Figure 6

 6 Figure 6 shows the DFTB/3OB_D4 conformers selected for the TCID modeling of the dissociation of the [amb 5S +Zn(II)+NTA] -complex into the products [amb 5S +Zn(II)]  + NTA (right) and [NTA+Zn(II)]  + amb 5S (left). The L-J Ω He for [amb 5S +Zn(II)+NTA] -and [amb 5S +Zn(II)]  (Table 1, Fig 4a) were in best agreement with the TWIMMS Ω He . The amb 5S , NTA and [NTA+Zn(II)]  conformers were the lowest energy conformers located, because their Ω He could not be measured by the PA calibration; amb 5S and NTA are neutral species and [NTA+Zn(II)]  was too small in size.

Figure 6 .

 6 Figure 6. The DFTB/3OB_D4 conformers of the [amb 5S +Zn(II)+NTA] -ternary complex and the products [amb 5S +Zn(II)]  + NTA (right) and [NTA+Zn(II)]  + amb 5S (left). The molecular parameters of these conformers were used in the modelling of the TCID reaction to extract the 0 K threshold energies. The representative potential energy surface illustrates the density of states of the energized [amb 5S +Zn(II) +NTA]  complex and the sum of states of the two product channels. The threshold energies, E 1 and E 2 , indicate the 0 K enthalpy changes for the two reactions. The DFTB/3OB_D4 conformer [amb 5S +Zn(II)+NTA] -has the substituent groups of His 1 , Cys 7 and the carboxylate terminus (C-terminus), with a carboxyl (C 1 ) and carboxylate (C 2 ) from the NTA, occupying five sites of a distorted octahedral Zn(II) coordination geometry. The three negatively charged sites of Cys 7 , C-terminus and the carboxylate (C 2 ) with the 2+ charge from Zn(II) gives the overall -1 charge of the ternary complex. For [amb 5S +Zn(II)] -the Zn(II) the substituent groups of Cys 2 and Cys 7 , backbone carbonyl group of Cys 2 , and C-terminus coordinated Zn(II) in a distorted tetrahedral geometry. The reaction mechanism for the [amb 5S +Zn(II)+NTA] -conformer to dissociate into the [amb 5S +Zn(II)] -+

Figure 7

 7 Figure 7 shows the DFTB/3OB_D4 conformers of [amb 5T +Zn(II)+NTA] -and the products [amb 5T +Zn(II)]  + NTA (right) and [NTA+Zn(II)]  + amb 5T (left) selected for the TCID modeling. The [amb 5T +Zn(II)+NTA] -complex exhibits Asp 1 and Cys 7 coordination of Zn(II) and amine and two carboxylates (C 1 and C 2 ) from NTA in a distorted bipyramidal geometry. These are the four negativelycharged sites that are balanced by the Zn(II) ion and His 2 imidazolium group to give the overall -1 charge of the complex. The [amb 5T +Zn(II)] -complex exhibits Asp 1 , His 2 , Cys 7 , and C-terminus coordination of Zn(II) via a distorted tetrahedral geometry. The dissociation of [amb 5T +Zn(II)+NTA] -into the [amb 5T +Zn(II)] -conformer requires proton transfers from His 2 and the carboxyl terminus to the two carboxylate sites (C 1 and C 2 ) of NTA, which His 2 and the C-terminus will subsequently displace in coordinating Zn(II).

Figure 7 .

 7 Figure 7. The DFTB/3OB_D4 conformers used in the TCID modeling of the dissociation of the [amb 5T +Zn(II)+NTA] -complex (center) into its products [amb 5T +Zn(II)]  + NTA (right) and [NTA+Zn(II)]  + amb 5T (left). The representative potential energy surface illustrates the energized ternary complex dissociating into the two product channels and indicates the density of states of the ternary complex and the sum of states of the products. The threshold energies, E 1 and E 2 , indicate the 0 K enthalpy changes for the two reactions.

3. 3 Figure 8 7 )Figure 8 .

 3878 Figure8shows the competitive TCID fits to the E cm -dependent  p convoluted over the energy distributions available during the reaction. The unconvoluted model (not shown) predicts the threshold behavior at 0 K, which are equal to the 0 K enthalpies of dissociation (H 0 ) for the reactions 6 and 7.[amb 5 +Zn(II)+NTA]  → [amb 5 +Zn(II)]  + NTA(6)

Table 2 .

 2 Fig 7, 8b) or PM6 conformers (Fig S10, S12), indicating the His 1 -Cys 2 substituent groups of amb 5S have a higher Zn(II) affinity than the Asp 1 -His 2 of amb 5T . The amb 5T also exhibits a higher Zn(II) affinity than the amb 5A and amb 5H which both contain the Tyr 5 -His 6 residues whereas, amb 5T contains the Gly 5 -Gly 6 sequence. Add discussion of amb5-and His-Cys-C-term salt-bridges and C-term-Tyr hydrogen bond. Comparison of the difference in the competitive TCID 0 K enthalpies (H 0 ) for reactions 6 and 7 shown in the script. The difference,  Zn H 0 = H 0 (6) -H 0 (7) =  Zn H 0 (amb 5 ) - Zn H 0 (NTA), gives a relative gas-phase Zn(II) affinity scale for the amb 5 species studied here and in our previous research.[START_REF] Corrales | Thermochemical Studies of Ni(II) and Zn(II) Ternary Complexes using Ion Mobility-Mass Spectrometry[END_REF] Name: primary structure or formula  Zn H 0 (eV) amb 5S : ac-His-Cys-Gly-Pro-Gly-Gly-Cys -0.41 (-0.44, -0.52) 1 amb 5T : ac-Asp-His-Gly-Pro-Gly-Gly-Cys -0.35 (-0.40) 1 amb 5A : ac-His-Cys-Gly-Pro-Tyr-His-Cys -0.22 amb 5H : ac-Asp-Cys-Gly-Pro-Tyr-His-Cys -0.15 NTA: N(CH 2 COOH) 3 0

Table 1 .

 1 Comparison of the average TWIMMS Ω He (Å 2 ) and the L-J Ω He of selected low-energy stationary states (static) initially located by geometry-optimizations and thermochemical analyses by PM6, further geometry-optimized by DFTB/3OB_D4 (DFTB static), and molecular dynamics simulations of the DFTB conformers at 300 K (DFTB-MD). The PM6 conformers are shown in Figures S2 to S7 in the Supporting Information and are identified in the Table.The bold values show the [amb 5 +Zn(II)+NTA] -and [amb 5 +Zn(II)]  conformers with L-J Ω He that best agreed with the TWIMMS Ω He and the amb 5 with the lowest thermochemical analyses, selected to use in the TCID modeling.

		[amb 5S +Zn(II)+NTA] 		[amb 5S +Zn(II)] 			amb 5S
	TWIMMS		196 ± 4			168 ± 3			-
		S2a	S2b	S2c	S3a	S3b	S3c	S4a	S4b
	PM6 static	194 ± 1 204 ± 1 195 ± 1 174 ± 1 163 ± 1 168 ± 1 169 ± 1	166 ± 1
	DFTB static	187 ± 1 199 ± 1 197 ± 1 175 ± 1 163 ± 1 163 ± 1 165 ± 1	165 ± 1
	DFTB-MD	192 ± 2 203 ± 3 196 ± 2 174 ± 3 163 ± 3 166 ± 2 169 ± 3	169 ± 2
		[amb 5T +Zn(II)+NTA] 		[amb 5T +Zn(II)] 			amb 5T
	TWIMMS		195 ± 4			166 ± 3			-
		S5a	S5b	S5c	S6a	S6b	-	S7a	S7b
	PM6 static	207 ± 1 196 ± 1 207 ± 1 170 ± 1 167 ± 1	-	173 ± 1	175 ± 1
	DFTB static	199 ± 1 196 ± 1 204 ± 1 169 ± 1 168 ± 1	-	173 ± 1	173 ± 1
	DFTB-MD	202 ± 2 201 ± 3 209 ± 2 175 ± 4 167 ± 3	-	170 ± 3	174 ± 3

Notably, the average Ω He values obtained from MD simulations, shown in Table 1, are in agreement with experiments, and they are similar or slightly different (mostly larger) than what was

In brackets are the differences in  Zn H 0 measured by TCID using the PM6 molecular parameters shown in the Supporting Information in FiguresS8, S9, S10, S11 and S12.4. ConclusionsThis research further extended the competitive TCID methodologies using the traveling-wave ion mobility-mass spectrometry (TWIMMS) platform[START_REF] Pringle | An investigation of the mobility separation of some peptide and protein ions using a new hybrid quadrupole/travelling wave IMS/oa-ToF instrument[END_REF] and whether it provides the relative gas-phase Zn(II) affinities for alternative metal binding (amb) heptapeptides. The competitive TCID analyses was applied

Acknowledgements

This work was supported by the National Science Foundation (1764436), NSF REU program (CHE-1659852), NSF instrument support (MRI-0821247), and Welch Foundation (T-0014). We thank Kent M.

Ervin (University of Nevada -Reno) and Peter B. Armentrout (University of Utah) for sharing the CRUNCH program. We also thank Michael T. Bowers (University of California -Santa Barbara) for sharing the Sigma program.


Salah Bouregbi
email: salihbourg@yahoo.fr

Tension and Contention in the Translation of the Literary Text: The Real Dilemma

Keywords: rendering, interpretation, literary meaning, translation, rubaiyyat

Does translation of the literary text really need a theory? If yes which one among so many, which complicate more than simplify the matter? Which strategy do we adopt to at least communicate something of the original to a target reader, who does not know anything of the source language? The key problem is the meaning. Is it really grasped? If yes, is it of the text, or of the author, or of the reader? Meaning is not restricted to linguistic parameters; it is more cognitive and essentially based on the interpreter's own world knowledge. The text is not only a product but essentially an on-going process of meaning. Though it has precise time and space when produced, it is, nonetheless, timeless and spaceless. When we animate it, through reading, it becomes a text within the scope of a new space and a new time. That is, the meaning in the process of translation becomes anew. The text is autonomous and its autonomy makes it have its own specificity and existence. And so, the meaning in/of the text is ever-changing: there is no one meaning in/of the text, as there is no one reader of the text.

Introduction

Does translation really need a theory? If yes which one among so many, which complicate more than simplify the matter? Which strategy do we adopt to, at least, communicate something of the original to a target reader, who does not know anything of the source language? In any case, the crux of the matter is meaning: how can we get it? Is it really grasped? If yes, is it of the text, or the author, or the reader? Are understanding and meaning interchangeable? Is understanding a diagnostic process of meaning?

Meaning(s) and the Literary Text

Meaning of/in the literary text is problematic: it is not only restricted to linguistic parameters; it is rather more intentional, hermeneutic, cognitive and essentially based on the interpreter's own world knowledge. In Critical Discourse Analysis, Terry Locke maintains that: -Not only do different types of text require different ways of reading, but the same text can also be read in different ways to generate different meanings. Textual meaning becomes multiple and therefore indeterminate.‖ [START_REF] Baker | The Status of Equivalence in Translation Studies: An Appraisal[END_REF] The text is not only a product but essentially an on-going process of meaning. Though it has precise time and space when produced, it is, nonetheless, timeless and spaceless. That is, its space and time are dialogically related to its act of reading: its now. When we read and animate it, we make it exist within a new space and time.It constructs its being through the process of reading. In other words, meaning is an interactive event between the text and the reader. The critic Norman Fairclough points that: -[The text] whose primary semiotic form is language increasingly combine language with other semiotic forms. The implicit content of a text is a sort of halfway house between presence and absence.‖ [START_REF] Fairclough | Critical Discourse Analysis: The Critical Study of Language[END_REF] Fairclough believes that any meaning in a literary text is preconstructed. This preconception of meaning paves the way for the reader to get within the text and finds out what he has already constructed. Fairclough maintains that: -The concept of «pre-constructed» has been used to give an intertextual understanding of implicit content (presupposition); the unsaid of a text, what it takes as given, is taken as the already-said-elsewhere, the form in which a text is shaped and penetrated by (ideological) elements from domains of prior textual practice.‖ [START_REF] Fischer-Starcke | Corpus Linguistics in Literary Analysis Jane Austen and her Contemporaries[END_REF] In the same vein, the critic H.G. Widdowson points out the instability of meaning in creative writing, mainly fiction and poetry. He writes:

The text is there at first hand, stable, continuous, well-ordered, fixed on a page, or on a screen. But these very features of the textual record can mislead us into thinking that its relationship with the discourse that gave rise to it is relatively unproblematic, and we are drawn into the delusion that meaning is inscribed in the text itself, and that what the writer intended to mean can be discovered, inferred, directly from textual evidence.

[….] The orderliness and apparent completeness of written text disguises the fact that it too is only a partial record of intended meaning.

The Literary text poses a great problem of interpretation: it holds many stances of interpretations. Its process of meaning is multiple and based on the interpreter's intention(s). Widdowson states that: -The writer enacts a discourse with a projected reader who may be very different from the actual readers who derive their own discourse from the text. [….] And unlike spoken conversation, there can be no on-line negotiation to enable the two parties to converge on a common understanding. In this respect, the stability of the text conceals an intrinsic instability of meaning.‖ [START_REF] Garcia-Landa | Translation Theory and the Problem of Equivalence[END_REF] So, what we get as meaning from the text is only a meaning of one's own assumption. Even, the same reader could find a series of meanings through his different diverse readings of the same text. In other words, your own intentions will, subsequently, chase the author out of the context of his own reality.

The text is not only a linguistic matter: a system of codes, sentences and expressions dissociated from contexts and insights. It is a whole, and its interdependent relationship between form and content weave its own texture. Bettina Fischer-Starcke points out that: the meaning is not a linguistic phenomenon, which could be found out through linguistic analyses. Rather, it is text-internal analysis that -gives a new perspective on the data, so that the researcher can detect new meanings even in a widely discussed text. The detailed linguistic analysis allows to find meanings, which are virtually invisible in an intuitive approach to the data as in literary studies.‖6 James Paul Gee maintains that there are two major elements that affect the text's meaning(s): the -who‖ and the -what‖. He writes: [START_REF] Hall | Our Monthly Gossip[END_REF] In the same context, Ernest Leopore and Kirk Ludwig acknowledge the -ingraspability‖ of the literary text. Words on their ownseparatelyare significant, and they cause no difficulty in their comprehension. But being within a sentence, the sentence within a paragraph, and the paragraph within a text, the meaning is no longer the sum of the meanings of each word, but it steps beyond such significances. This sum, as a whole, gets a new sense dictated by the intentionality of the reader(s). Leopore and Ludwig point out:

If I have
The meaningful complexes in a language obviously are understood on the basis of their parts and mode of combination. The illusion of understanding is increased when we realize that this makes available to us the apparatus of quantification theory in giving a systematic account of the meanings of complex expressions on the basis of the meanings of their parts and mode of combination. [START_REF] Heron-Allen | Fitzgerald's Rubaiyat of Omar Khayyam[END_REF] If the text resists to its reader, or if the reader builds up its significance on his own intention, then: how can we translate the text? Or put forward: what do we exactly portrait? Anthony Pym claims that: -Meaning transfer is thus an assumptioncertainly a social illusionoperative in the use of translations as translations. Yet it is not ubiquitous. Inasmuch as there are users for whom the source text is unavailable, this assumption of meaning transfer is specifically external to actual translation processes. No translator or translation critic need believe that translation is the transfer of stable meaning. Indeed, inasmuch as there is a plurality of translators for whom source-text meanings differ.‖ [START_REF] Lepore | Ontology in the Theory of Meaning[END_REF] In his article -Theories of Translation,‖ Eugene A. Nida points out that: -The basic problem of formulating an adequate theory of translation is the fact that translation actually takes place in our brains, and we do not know precisely what actually happens. There are no complete synonyms within a language or between different languages, but such a statement seems evidently incorrect because almost all dictionaries have extensive lists of synonyms, for example, sets such as rich/wealthy and run/race. But such sets of synonyms are normally limited to a restricted set of contexts.‖ [START_REF] Locke | Critical Discourse Analysis[END_REF] And so, the problem of translation is within the text at the first degree, and the text and the reader at a second degree. Commenting on Nida's definition of translation, Shiyang Ran writes:-If there is an absolute correct translation, then we have to face the question that «who can identify the absolute correct translation?» [START_REF] Heron-Allen | Fitzgerald's Rubaiyat of Omar Khayyam[END_REF] Ernest Lepore and Kirk Ludwig, -Ontology in the Theory of Meaning,‖ International Journal of Philosophical Studies 14, 3 (2006) An expert or an ordinary reader? Are their opinions the same? [….] As every estimator is characteristic of his/her personal class, any valuation is characteristic of relative class feature. Readers decide to accept or reject translations, and different types of reader will require different types of translation. A closest natural translation for highly qualified intellectuals may not be the closest natural one for common people or ordinary citizens.‖ [START_REF] Nida | Theories of Translation[END_REF] What Ran wants to transmit is that all meanings are contextual, and all contexts are dialogically related to the reader through his intention and the ‗what' to discover. In the process of translation, the operation becomes doubly complicated since, by definition, two languages and, thus, two cultures and two societies are involved. [START_REF] Norton | Comments on Fitzgerald's Poem[END_REF] The literary text is an iceberg: What it hides is more than what it shows. Like mercury, it slips from your hands whenever you try to grasp its meaning(s). Furthermore, involvement within the choice of words and expressions makes the translator/interpreter reconstruct a context proper to his own strategy and, thus, makes another text out of the relics of the original. The critic Maria Tymoczko maintains that: -Translations themselves form subsystems of textual systemsnotably literary systemsand collectively can be grouped by parameters such as function, audience, text type, formal effects, and patronage.‖ [START_REF]Trinity College London, qtd Alfred McKinley Terhume The Life of Edward Fitzgerald: Translator of -The Rubaiyat of Omar Khayyam[END_REF] One should not forget that the duty of the translator is to transfer for us a source text and to enable us to read the text as if it was written in the target language. But, is he able to do it? The embodiment of the source text is not made in a vacuum: its texture both formal and contextual is trailered to a degree that we cannot take even a fibre of its onenessits constitution. We can dislocate or relocate its style and content and make it foreign to its sourceoriginal: there is a great risk of transformation because any act of translation is an act of omission and addition. Laurence Venuti speaks of illusory translation. The text you read seems to be a foreign text that you accept as such because of the ingenuity of the translator, who recreates it in a way that makes you appreciate both the form (his from) and the style (his style) and you claim its originality. Venuti points out:

The illusion of transparency is an effect of fluent discourse, of the translator's effort to insure easy readability by adhering to current usage, maintaining continuous syntax, fixing a precise meaning. What is so remarkable here is that this illusory effect conceals the numerous conditions under which the translation is made, starting with the translator's crucial intervention in the foreign text. [START_REF] Pasha | Trans. The Rubaiyat of Omar Khayyam[END_REF] But this invisibility Venuti is talking about can in no way be possible: the more the translator is invisible, the more the text becomes his ownthe more he possesses it. He becomes his authorhis creator. In other words, invisibility excludes the author and corrupts the text.

There is no adequate, equivalent style and expression in/between languages, even those of the same roots. And no meaning is ever possible without these expressions and stylistic patterns. Even equivalences pose a problem. Meaning we derive, or deduce from equivalence, is not the meaning of the text, but the meaning of a text suggested by the reading of the translator. Equivalence is, then, what is intended to be a meaning. In this context, the critic Mona Baker states that:

The notion of equivalent effect is also linked to the idea of reproducing the -intention‖ of the source author, i.e., emphasizing the equivalence of intended meaning. This is also highly problematic because it assumes that the translator -understands‖ rather than -interprets‖ the source textthat somehow he or she has direct access to the communicative intentions of the original author. But translators cannot know with any certainty what the source author intended to convey, especially where there is a large temporal gap between the source and target texts. All they can do is try to interpret it, so that any theory or model based on some notion of equivalence of intention would be impossible to verify. [START_REF] Pym | Doubts about Deconstruction as a General Theory of Translation[END_REF] The text seems for us, as readers of the target, as if it was an original one because of the effect the translator uses in his formulaic and imitating narrative. This illusory artefact makes us believe him and accept the text as a good translation and what we read must be the original, but, unfortunately, it is not.

In his article -Translation Theory and the Problem of Equivalence,‖Mariano Garcia-Landa raises such problem of equivalence and its inadequacy with meaning transfer. He thinks that equivalence exists, but the matter is what/how do we transfer? He writes: -The problem with equivalence is this. We know that equivalence is the real thing in translation, that there is no translation if there is no equivalence between the original text and the translated text. And we know of course that equivalence exists, that is not the real problem.‖ [START_REF] Ran | Philosophical Interpretation on E.A. Nida's Definition of Translation[END_REF] He maintains that translating is another way of speaking of conveying messages through signs, and through theses signs we produce perceptions.-But the problem is that these perceptions, which are produced through these sign chains, are different from these sign chains. This means that translation is the reproduction of the same perceptions which are produced with another sign system of another language.‖17 This is somehow a mirage! And so; what about poetry whose problem is double-edged: problem of form (meter, rhyme, rhythm) and content (context, in-text, intention). Poetry is, then, a real challenge for translators!

Poetry and the Problem of Meaning Transfer in Translation:

Form and content cannot be separate in poetry. It is like a coin whose value is based on its both faces. James Paul Gee states that: -Content is highly languagebound and this is what makes translation of poetry more difficult than the other types of translations. Poetry makes possessing components such as rhythm, rhyme, tone, deviation from the institutionalized linguistic code, musicality expressed through meters and cadence, etc., arouses pessimistic statements on the scope of its translatability that exceeds those affirmative ones.‖ [START_REF] Tymoczko | General Considerations About Theory[END_REF]

O. Khayyam's Rubaiyyat and the Contentious Versions of E. Fitzgerald and J. Pasha

Two translations of Omar Khayyam's Rubaiyat into English seem to be very problematic: Edward Fitzgerald's (1857-59) and John Pasha's (1913) versions are very disparate to be authentic and faithful translations to the original. What do we read? Who is nearest to Khayyam: Edward Fitzgerald or John Pasha? Why do we have such diversities in form and content? The problem seems to be a question of meaning and how does the translator render the quatrains' expressions and words into English. In his comments on Fitzgerald's translation, the critic C. Eliot Norton assumes that:

He [Fitzgerald] is to be called -translator‖ only in default of a better word, one which should express the poetic transfusion of a poetic spirit from one language to another, and the representation of the ideas and images of the original in a form not altogether diverse from their own, but perfectly adopted to the new conditions of time, place, custom, and the habit of the mind in which they appear. [START_REF] Venuti | The Translator's Invisibility: A History of Translation[END_REF] The critic reviewer of Lippincott's Magazine, Edward Hall, praised the poem and wrote: -He [Fitzgerald] has gone far to prove that the acceptableness among us of Oriental poetry may depend very largely on the skill with which it is transplanted into our language.‖ [START_REF] Widdowson | Context, Pretext: Critical Issues in Discourse Analysis[END_REF] So many critics glorify Fitzgerald's version. But can we really acknowledge its originality? Are all these grandiloquent words adequate and ever-inciting? Does the poem hold the spirit of Omar Khayyam or Edward Fitzgerald's? Is it a mediator of both souls and philosophies? Or just has a total autonomy: It is from both, yet negates both? It just becomes another text for another reader of another understanding?

But before embarking on such contentious questions, it is of paramount importance to have a closer look on the nature of the meter in Persian poetry then draw a kind of similarity between the English and the Persian meters, and how did Fitzgerald deal with all these in his translation?

What is a Rubai in Persian literature? The critic, Alfred Mckinley Terhume, explains for us the rubai and its equivalence in English meters as follows: -It is simply for convenience that the Persian term rubai is translated into English «quatrain». Actually, the rubai is a two-lined stanza which breaks naturally into four lines of the English quatrain. In every variety of Persian poetry, the unit is the bayt, a line which consists of six or eight feet. Each bayt in a rubai is divided into two symmetrical halves called misra. Usually, the first, second and fourth misra, rhyme, resulting in the aa b a pattern used in English translations. In other words, a rubai consists of two lines divided into hemistichs with the first, second, and fourth hemistichs rhyming.‖ [START_REF] Wright | The Life of Edward Fitzgerald: Translator of The Rubaiyat of Omar Khayyam[END_REF] In this translation, Fitzgerald adopted the rhyme pattern (a a b a) which predominates in the original, but he simplified the rhyme itself. Many critics contend that Fitzgerald has translated his personal outlook of the spirit/philosophy of Omar Khayyam rather than the quatrains of The Rubaiyat. Edward Hemon-Allen claims that Fitzgerald has not faithfully restricted himself to the quatrains of Khayyam; the first stanza, for example, is entirely his own. 22 Hemon-Allen spent around twelve years surveying the entire range of Fitzgerald's Persian studies and tracing his quatrains to their sources. His object was: -to set at rest, once or [START_REF] Widdowson | Context, Pretext: Critical Issues in Discourse Analysis[END_REF] Edward Hall, -Our Monthly Gossip,‖ In Lippincott's Magazine XV (1875), 261. [START_REF] Wright | The Life of Edward Fitzgerald: Translator of The Rubaiyat of Omar Khayyam[END_REF] The second version of Rubaiyat in English is that of Johnson Pasha. This version does not in any way lack dexterity to that of Fitzgerald. His translation was published in 1913, years after that of Fitzgerald. In his preface to such translation, he wrote underlining the difficulties he faced in the course of translation:

I have, however, subject it [The Rubaiyat] to some revision, and hope that the more important errors have been corrected, and that it now presents a fairly accurate idea of the original meaning. I think that the great majority of the quatrains are, if not a literal, at least a fairly close rendering of the original text, but I have not hesitated to add expressions not to be found in the original where it seemed to me clear that anything like a simple translation of the original words not convey the same ideas as the Persian. 28 He even claimed that the word -khish‖ in the quatrain sixty seven (67) was wrongly translated as -spear‖ not -brick‖ as usually rendered. -There is, of course, much (sic) repetition, but though this greatly increases the difficulty of any attempt to render into verse without contact repetition of the same phrases. [….] There is generally something new to be found‖. 29 About the feet he has chosen for the meter, he said: -I have feet justified in serving the needs of rhyme by speaking of the flower's thanks for new born-life.‖ He adds -I have departed from the tensyllable line in many instances, and have even exceeded the limits of the rubai, but I can only urge in externation that I have found the endeavour to turn seven hundred sixty two (762) quatrains of Persian into seven hundred sixty-two (762) quatrains of English a task of great difficulty, and I hope for the indulgence of those who may care to read.‖ 30

Conclusion

Rendering seems to be the only solution to literary translation mainly in poetry. But rendering, itself, is dialogically related to the moment of reading and of transfer! But this transfer is in no way of the text, or the author or the reader; yet, it is from the text and the author and the reader.

Bibliography:

14

  Lawrence Venuti, The Translator's Invisibility: A History of Translation (London, and New York: Palgrave, 1995), 8. 15 Mona Baker, -The Status of Equivalence in Translation Studies: An Appraisal,‖ in Centre for Translation & Intercultural Studies (Manchester: University of Manchester, 2004), 3. 16 Mariano Garcia-Landa, -Translation Theory and the Problem of Equivalence,‖ Hermēneus Revista de Traduccion e Interpretacion 2 (2000), 1.

26

  Aldous Wright, -Literary Remains‖, VII, 18, in Alfred McKinley Terhume, The Life of Edward Fitzgerald: Translator of The Rubaiyat of Omar Khayyam (London, New Haven: Oxford University Press, and Yale University Press, 1947), 229. 27 Fitzgerald qtd Alfred McKinley Terhume, The Life of Edward Fitzgerald: Translator of The Rubaiyatof Omar Khayyam (London, and New Haven: Oxford University Press, and Yale University Press, 1947), 229. 28 Johnson Pasha, The Rubaiyat of Omar Khayyam, trans. Johnson Pasha (London: Kegan Paul & Trench, Trubner & Co, 1913), 5. 29 Johnson Pasha, -The Preface,‖ in The Rubaiyat of Omar Khayyam, trans. Johnson Pasha (London: Kegan Paul & Trench, Trubner & Co, 1913), vi.

no idea who you are and what you are doing, then I cannot make sense of

  what you have said, written, or done.[….] What I mean by a -who‖ is a sociallysituated identity. What I mean by a -what‖ is a socially-situated activity that the utterance helps to constitute. Finally, we can point out that whos and whats are not really discrete and separable. You are who you are partly through what you are doing and what you are doing is partly recognized for what it is by who is doing it.

  Alfred McKinley Terhume, The Life of Edward Fitzgerald: Translator of The Rubaiyatof Omar Khayyam (London, and New Haven: Oxford University Press, and Yale University Press, 1947), 220.22 Edward Heron-Allen, Fitzgerald's Rubaiyat of Omar Khayyam (London: Bernard Quaritch, 1899), 5.forever, the vexed quatrain of how Edward Fitzgerald's incomparable poem may be regarded far as an adaptation, and how far an original work.‖ 23 His observations are astonishingly remarkable: Forty Nine (49) quatrains are faithful and beautiful paraphrases of single quatrains to be found in the Onsley or Calcutta or both.  Forty Four (44) quatrains are more than one quatrain and may be termed -composite‖ quatrains.  Two (2) quatrains are inspired by Fitzgerald only in Nicolas' text.  Two (2) quatrains reflecting the whole spirit of the original poem.  Two (2) quatrains are exclusively due to the influence of the Mantik Uttair of Ferid Id di Attar.  Two (2) quatrains primarily inspired by Omar were influenced by the Odes of Hafiz. The total accounts for 101 stanzas make up the poem in its final form.24 Furthermore, Hemon-Allen claims that Fitzgerald's poem is not wholly adapted from the original but various translated and non-translated references, besides some quatrains of Khayyam that are not of his Rubaiyat: *Quatrains forty six (46) and ninety eight (98) are inspired by J. B. Nicolas. *Quatrains thirty three (33) and thirty four (34) are Atter's. *Quatrains two (2) and three (3) are Hafiz's.*Quatrains five (5) and eighty-six (86) hold no reference to any quotation in the original, but refer to Omar's philosophy.25 Fitzgerald had studied three different collections of Omar's quatrains before his poem reached its final form: The Onsley Manuscript at the Boldean Library, Nicolas's translation, and the Calcutta Manuscript of Bengal Society. The Boldean contains 158 stanzas; Calcutta Manuscript counts 516 stanzas, and J. B. Nicolas's translation of 1867 contains 464 Stanzas. Fitzgerald's contains 101 stanzas. His version seems to be a distillation of Omar Khayyam's thoughts and philosophy.Fitzgerald is skilled in the reproduction of the sense of the original. Quatrain eighty one (81) has been much discussed. In his 1903 edition, Aldus Wright quotes the following from a letter written to him by Cowell: -There is no original for the line about the snake: I have looked for it in vain in Nicolas; but I have always supposed that the last line is Fitzgerald's mistake version of quatrain 236 in Nicolas's edition.‖26 In a letter to Mrs Cowell, December 17, 1867, Fitzgerald acknowledged that: -You know I have translated none literally, and have generally mashed up two-ormore-into one.‖ 27

	Stanza 81:
	Oh Thou, who Man of baser Earth didst make,
	And ev'n with Paradise devise the Snake:
	For all the Sin wherewith the Face of Man
	Is blacken'd -Man's forgiveness give -and take!

H. G. Widdowson, Text, Context, Pretext: Critical Issues in Discourse Analysis (New York: Blackwell Publishers, 2004), 10.

Widdowson, Text, Context, Pretext,[START_REF] Nida | Theories of Translation[END_REF]

Bettina Fischer-Starcke, Corpus Linguistics in Literary Analysis Jane Austen and her Contemporaries (New York and London: Continuum International Publishing Group, 2010), 6.

James Paul Gee, An Introduction to Discourse Analysis: Theory and Method (London: The Taylor & Francis e-Library, 2001), 13/14.

Shiyang Ran, -Philosophical Interpretation on E.A. Nida's Definition of Translation,‖ Asian Social Science 5, 10 (2009), 45.

Ran, -Philosophical Interpretation,‖ 45.

Maria Tymoczko, -General Considerations About Theory,‖ in The Encyclopedia of Applied Linguistics.[START_REF] Baker | The Status of Equivalence in Translation Studies: An Appraisal[END_REF][START_REF] Fairclough | Critical Discourse Analysis: The Critical Study of Language[END_REF][START_REF] Fischer-Starcke | Corpus Linguistics in Literary Analysis Jane Austen and her Contemporaries[END_REF][START_REF] Fitzgerald | Trans. Rubaiyat of Omar Khayyam[END_REF][START_REF] Garcia-Landa | Translation Theory and the Problem of Equivalence[END_REF][START_REF] Gee | An Introduction to Discourse Analysis: Theory and Method[END_REF][START_REF] Hall | Our Monthly Gossip[END_REF][START_REF] Heron-Allen | Fitzgerald's Rubaiyat of Omar Khayyam[END_REF][START_REF] Lepore | Ontology in the Theory of Meaning[END_REF][START_REF] Locke | Critical Discourse Analysis[END_REF]. ed. Carol A. Chapelle (London, and New York: Publishing Ltd. 2013), 5.

Garcia-Landa, -Translation Theory,‖ 2.

James Paul Gee, An Introduction to Discourse Analysis: Theory and Method (London: The Taylor & Francis e-Library, 2001), 159.

Charles Eliot Norton, -Comments on Fitzgerald's Poem,‖ Norton American Review CIX (1869), 575-76.

Heron-Allen, Fitzgerald's Rubaiyat of Omar Khayyam, 5-6.

Heron-Allen, -The Preface,‖ at Fitzgerald's Rubaiyat of Omar Khayyam, xi-xii.