Hydration Of Amino Acids Research Articles

Does Positron Attachment Take Place in Water Solution?

We performed a computational study of positron attachment to hydrated amino acids, namely glycine, alanine, and proline in the zwitterionic form. We combined the sequential quantum mechanics/molecular mechanics (s-QM/MM) method with various levels of any particle molecular orbital (APMO) calculations. Consistent with previous studies, our calculations indicate the formation of energetically stable states for the isolated and microsolvated amino acids, in which the positron localizes around the carboxylate group. However, for the larger clusters, composed of 7 to 40 water molecules, hydrogen bonding between the solute and solvent molecules disfavors positron attachment to the amino acids, giving rise to surface states in which the positron is located around the water-vacuum interface. The analysis of positron binding energies, positronic orbitals, radial probability distributions, and annihilation rates consistently pointed out the change from positron-solute to positron-solvent states. Even with the inclusion of an electrostatic embedding around the aggregates, the positrons did not localize around the solute. Positron attachment to molecules in the gas phase is a well-established fact. The existence of hydrated positronic molecules could also be expected from the analogy with transient anion states, which are believed to participate in radiation damage. Our results indicate that positron attachment to hydrated biomolecules, even to zwitterions with negatively charged carboxylated groups, would not take place. For the larger clusters, in which positron-water interactions are favored, the calculations indicate an unexpectedly large contribution of the core orbitals to the annihilation rates, between 15 and 20%. Finally, we explored correlations between positron binding energies (PBEs) and dipole moments, as well as annihilation rates and PBEs, consistent with previous studies for smaller clusters.

Unravelling molecular origins of improved tribological properties of amino acid ionic liquid water-based lubricants

In the quest for sustainable lubrication, this study explores the potential of water-based lubricants (WBLs) with amino acid ionic liquid (AAIL) additives. The research combines experimental and reactive molecular dynamics (MD) simulations to assess the tribological and rheological enhancements provided by AAILs. Specifically, tetrabutylphosphonium (P4444) cations paired with Serine (Ser) and Tryptophan (Trp) anions were mixed into water to create AAIL WBLs. The introduction of AAILs significantly improved the lubricants’ rheological properties and reduced the coefficient of friction by up to 34 %. This reduction is attributed to the formation of hydration shells around the amino acid anions, which create a chemically adsorbed tribofilm on iron oxide surfaces, and P4444 cations that establish a load-bearing layer in the middle regions of the lubricant. This dual-layer structure, supported by hydration lubrication, effectively maintains lubricant fluidity while bearing substantial loads. Among the AAIL WBLs tested, those with a thicker, more stable, hydrated amino acid tribofilm demonstrated more significant friction reduction. These insights into the molecular mechanisms behind AAIL WBLs’ tribological behaviour underscore their promise as eco-friendly lubricants, contributing to advancing a circular economy in industries reliant on lubrication.

Choline chloride and amino acid solutions taste and hydration behavior with experimental thermodynamic properties and COSMO-PC-SAFT calculation

Aqueous amino acid solutions have been introduced as dietary supplements for both animals and humans. This study investigates the physicochemical properties of the solutions containing amino acids (l-glycine, d,l-alanine, l-proline), choline chloride, and water at temperature range of 288.15 to 318.15 K. The results show that increasing concentrations of amino acids and choline chloride lead to higher solution densities. Analysis of apparent molar volume (Vφ) and apparent molar isentropic compressibility (κφ) reveals that Vφ values increase with choline chloride concentration and temperature, indicating enhanced solute–solvent interactions, while κφ values decrease, suggesting increased solution compression. Thermodynamic analysis using the Redlich-Mayer model and COSMO-based modeling provides insights into molecular interactions. However, COSMO-based parameters show high average relative deviation percentage (ARD %) values, indicating poor predictive performance for the density of these systems. In contrast, the ePC-SAFT equation of state effectively predicts the densities, particularly for l-proline-based solutions, which show very low ARD % values, indicating high accuracy. The ePC-SAFT model also performs reasonably well for l-glycine solutions but shows poorer results for d,l-alanine-based solutions. The study also examines the sweetness and saltiness criteria (ASV and ASIC) of these solutions. The ASV values, which serve as a sweetness criterion, are higher than the ideal range of 0.5 < ASV < 0.7, suggesting an overly sweet taste. The ASIC values follow a similar trend, indicating increased saltiness. To achieve an appropriate grade of sweetness and saltiness, dilution to lower concentrations of the solution is recommended. Furthermore, the use of choline chloride is found to increase salt intake and enhance the taste of salt, which can be beneficial in amino acid supplements used in animal food.

Post-translational modification sites are present in hydrophilic cavities of alpha-synuclein, tau, FUS, and TDP-43 fibrils: A molecular dynamics study.

Hydration plays a crucial role in the refolding of intrinsically disordered proteins into amyloid fibrils; however, the specific interactions between water and protein that may contribute to this process are still unknown. In our previous studies of alpha-synuclein (aSyn), we have shown that waters confined in fibril cavities are stabilizing features of this pathological fold; and that amino acids that hydrogen bond with these confined waters modulate primary and seeded aggregation. Here, we extend our aSyn molecular dynamics (MD) simulations with three new polymorphs and correlate MD trajectory information with known post-translational modifications (PTMs) and experimental data. We show that cavity residues are more evolutionarily conserved than non-cavity residues and are enriched with PTM sites. As expected, the confinement within hydrophilic cavities results in more stably hydrated amino acids. Interestingly, cavity PTM sites display the longest protein-water hydrogen bond lifetimes, three-fold greater than non-PTM cavity sites. Utilizing the deep mutational screen dataset by Newberry et al. and the Thioflavin T aggregation review by Pancoe et al. parsed using a fibril cavity/non-cavity definition, we show that hydrophobic changes to amino acids in cavities have a larger effect on fitness and aggregation rate than residues outside cavities, supporting our hypothesis that these sites are involved in the inhibition of aSyn toxic fibrillization. Finally, we expand our study to include analysis of fibril structures of tau, FUS, TDP-43, prion, and hnRNPA1; all of which contained hydrated cavities, with tau, FUS, and TDP-43 recapitulating our PTM results in aSyn fibril cavities.

Formulating Inhibited Fluids for Stable Drilling Operations into Tanuma and Zubair Shales, Zubair Oilfield, Southern Iraq

Tanuma and Zubair formations are known as the most problematic intervals in Zubair Oilfield, and they cause wellbore instability due to possible shale-fluid interaction. It causes a vast loss of time dealing with various downhole problems (e.g., stuck pipe) which leads to an increase in overall well cost for the consequences (e.g., fishing and sidetrack). This paper aims to test shale samples with various laboratory tests for shale evaluation and drilling muds development. Shale's physical properties are described by using a stereomicroscope and the structures are observed with Scanning Electron Microscope. The shale reactivity and behavior are analyzed by using the cation exchange capacity testing and the capillary suction test is utilized for selecting shale inhibitor base. As a result, four drillings muds are formulated with different additives and approved by using the Linear Swelling Meter and the Hot Rolling experiments. Tanuma’s shale is at higher reactivity level, where it is moderate to high active shale than Zubair’s shale, which is at a low to moderately reactive formation. Microfractures and micropores are excited in both formations and potentially in Tanuma’s shale. The shale stability can be achieved by adding 8 % of KCl for Tanuma’s mud and 4% of KCl for Zubair’s mud. The filtration controls are contributed to seal the shale open structures and adding the Poly amino acid hydration suppressant reduced the risk of shale swelling significantly. The results can be used for designing drilling mud to reduce shale instability issues and the cost.

Laboratory Testing and Evaluating of Shale Interaction with Mud for Tanuma Shale formation in Southern Iraq

Rock failure during drilling is an important problem to be solved in petroleum technology. one of the most causes of rock failure is shale chemical interaction with drilling fluids. This interaction is changing the shale strength as well as its pore pressure relatively near the wellbore wall. In several oilfields in southern Iraq, drilling through the Tanuma formation is known as the most challenging operation due to its unstable behavior. Understanding the chemical reactions between shale and drilling fluid is determined by examining the features of shale and its behavior with drilling mud. Chemical interactions must be mitigated by the selection of suitable drilling mud with effective chemical additives. This study is describing the laboratory methods that concern testing and evaluating the shale instability encountered while drilling operations. The cutting samples are collected from the targeted formation and used to categorize shale reactivity levels and the required additives to inhibit the clay instability. These tests include the descriptive method with the various analytical technique of standard laboratory equipment. The shale testing techniques are the Scanning Electron Microscope (SEM), X-ray Diffraction, X-ray Fluorescence, Cation-Exchange, Capacity (CEC), and Capillary Suction Timer test (CST). Also, Linear swelling meter test (LSM) was performed to enhance the development plan. Tanuma formation contains moderately active clay with the presence of microfractures and micropores in its morphology. And it is controllable by using polymer muds with 8 % of inorganic inhibitor (e.g., KCL), filtration controls additives, and poly amino acid hydration suppressant which showed minimum swelling percentage.

Hydration of amino acids: An investigation using density functional theory

Herein, we have investigated the effect of hydration of seven amino acids (AAs) such as alanine, aspartic acid,cysteine, glutamine, lysine, methionine, and phenylalanine with different number of water molecules using density functional theory. Among the hydrophobic AAs, cysteine has the highest interaction with water whereas in hydrophilic AAs, aspartic acid has the highest interaction with water. With the increase in number of water molecules, it is noted that alanine forms the most stable complex with water and methionine+water complex has least stability.In addition, we have calculated the chemical descriptors like chemical potential, electronegativity, hardness, softness, electrophilicity index of AAs to validate their interaction with water molecules. Interestingly, the gas phase interaction energy results match with the trend of electrophilicity index valuesof AAs.

Force Field Benchmark of Amino Acids. 3. Hydration with Scaled Lennard-Jones Interactions.

Classical protein force fields were reported with too weak protein-water interactions relative to protein-protein interactions, leading to more compact structures and artificial protein aggregation. Here we investigated the impacts of scaled Lennard-Jones (LJ) interactions on the hydration of amino acids and the simulation of folded and intrinsically disordered proteins (IDPs). The obtained optimal scaling parameters reproduce accurately hydration free energies of neutral amino acid side chain analogues and do not affect the compactness and structural stability of folded proteins significantly. The scaling leads to less compact IDPs and varies from case to case. Strengthening the interactions between protein and water oxygen or hydrogen atoms by increasing the interacting LJ well depth (ε) appears more effective than weakening protein-protein interactions by reducing the interacting dispersion coefficients (C6). We demonstrate that weakening water-water interactions is a solution as well to obtaining more favorable protein-water interactions in an indirect way, although modern force fields like Amber ff19SB and a99SB-disp tend to use water models with strong water-water interactions. This is likely a compromise between strong protein-protein interactions and strong water-water interactions. Independent optimization of protein force fields and water models is therefore needed to make both interactions more close to reality, leading to good accuracy without bias or scaling.

Risk factors of mFOLFOX6-induced hyperammonemia in patients with colorectal cancer: an observational study.

FOLFOX therapy, a standard treatment for colorectal cancer (CRC), causes a rare, but serious adverse event, hyperammonemia. However, the risk factors of hyperammonemia remain unknown. We examined 74 patients who received mFOLFOX6 therapy with or without biologics for CRC between April 2013 and March 2018 in Yaizu City Hospital. Clinicopathological factors were retrospectively reviewed in association with hyperammonemia, and risk factors of hyperammonemia during mFOLFOX6 therapy were analyzed in 32 patients with the available data. Seven patients developed hyperammonemia, with onset exclusively on day 2 or 3 in the first cycle of therapy. They were treated with branched chain amino acid administration and hydration; however, one patient with stage G4 chronic kidney disease (CKD) died. By multivariate analysis, estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 was independently associated with hyperammonemia during FOLFOX therapy (odds ratio: 9.0, p = 0.040). Reduced eGFR is considered a risk factor of developing hyperammonemia during FOLFOX therapy. Serum ammonia levels should be monitored especially during the first cycle of FOLFOX therapy in patients with CKD stage G3 or higher.

Water Distribution and Clustering on the Lyophilized IgG1 Surface: Insight from Molecular Dynamics Simulations.

Water has a critical role in the stability of the higher-order structure of proteins. In addition, it is considered to be a major destabilization factor for the physical and chemical stability of freeze-dried proteins and peptides. Physical and chemical aspects of protein/water relationships are commonly studied with the use of water vapor sorption isotherms for amorphous lyophilized proteins, which, in turn, are commonly analyzed using the Brunauer-Emmett-Teller (BET) equation to obtain the parameters, Wm and CB. The parameter Wm is generally referred to as the "monolayer limit of adsorption" and has a narrow range of 6-8% for most proteins. In this study, the water distribution on an IgG1 surface is investigated by molecular dynamics (MD) simulations at different water contents. The monolayer of water molecules was found to have limited coverage of the protein surface, and the true monolayer coverage of the protein globule actually occurs at a hydration level above 30%. The distribution of water molecules on the IgG1 surface is also highly heterogeneous, and the heterogeneity is not considered in the BET theory. In this study, a mechanistic model has been developed to describe the water vapor sorption isotherm. This model is based on the analysis of the hydrogen bonding network extracted from the MD simulations. The model is consistent with the experimental Type-II isotherm, which is usually observed for proteins. The physical meaning of the BET monolayer was redefined as the onset of water cluster formation. A simple model to calculate the onset water level, Wm, is proposed based on the hydration of different amino acids, as determined from the MD simulations.

Spin-frustration with two quasi-degenerated spin states of a copper(II) heptanuclear complex obtained from an amino acid ligand.

The Cu(ii) heptanuclear complex (Cu7atac) was synthesised using the hydrated amino acid ligand 2-(5-amino-1H-1,2,4-triazol-3-yl)acetic acid (Hatac·H2O). Single crystal X-ray diffraction analysis revealed a μ3-hydroxo bridged Cu(ii) heptanuclear complex, consisting of two triangular subunits and one Cu(ii) ion as a bridge with the formula [Cu7(atac)6(μ3-OH)2(NO3)2(H2O)10](NO3)4. The magnetic behaviour of this discrete 0D complex shows strong antiferromagnetic couplings between Cu(ii) mediated by N,N bonding and an anti-anti modes of the carboxylate anion of the ligand atac-. The magnetic data were fitted considering a 3J model. To support the model used to fit the magnetic data of the Cu7atac complex, theoretical calculation methods (complete active space self-consistent field, CASSCF, density functional theory (DFT) using the UKS TPSS/Def2-TZVP//Def2-SVP level and periodic boundary conditions (PBC) using PBE/DZVP-MOLOPT-GTH) were performed to obtain the spin states, spin density map and J couplings. The theoretical results suggest that Cu7atac is a spin-frustrated complex in the ground state, in which the doublet spin state co-exists with the quartet spin state.

Dual-prism based terahertz time-domain attenuated total reflection spectroscopy and its application to characterise the hydration state of L-threonine in solution

To investigate the hydration state of amino acids, terahertz time-domain attenuated total internal reflection (THz TD-ATR) spectroscopy is often adopted to measure the complex permittivity. However, the classical THz TD-ATR spectroscopy system has only a single ATR prism and requires prism cleaning for different measuring modes, increasing the time consumed and easily introducing errors due to the changing environment. To accelerate the measurements and avoid the influence of environmental fluctuations, in this paper, we designed and built a dual-prism based THz TD-ATR spectroscopy: two ATR prisms with and without samples setting on the optical rail can be sequentially switched to optical systems for easily and rapidly collecting both sample and reference ATR spectra. According to the measurements of deionised water, the dual-prism based THz TD-ATR spectroscopy system can measure the sample complex permittivity rapidly and with high accuracy. The complex permittivity of L-threonine in aqueous solution is measured and analysed via the proposed system, and the hydration numbers of L-threonine solutions in different concentrations are quantitatively characterised. It is believed that the dual-prism based THz TD-ATR technique is a powerful tool for quickly and accurately investigating the hydration of amino acids.

Temperature-dependent volumetric and ultraacoustic studies of α-amino acids in aqueous acetylsalicylic acid drug solutions

Present paper reports the results of densimetry and ultrasonic velocimetry studies of solutions of glycine, l‑serine, l‑proline, l‑asparagine monohydrate and l‑arginine in aqueous non-steroidal anti-inflammatory acetylsalicylic acid as a function of its molality. For this purpose, density and ultrasonic velocimetry data were obtained at atmospheric pressure as a function of amino acid concentration at fixed acetylsalicylic acid concentration (m = 0.001, 0.005 or 0.010 mol·kg−1) and temperature (T = 303.15, 308.15 or 313.15 K). The density and ultrasonic velocity data have been used to calculated the apparent molar volume (V2, ϕ) and apparent molar isentropic compressibility (κS, 2, ϕ) of studied solutions. The standard molar volume (V2, ϕo) and compressibility (κS, 2, ϕ0) were determined by least least-squre fitting of respective apparent properties to the amino acid molality. Further, these data were used to calculate standard transfer volume (ΔtV2, ϕo) and compressibility (ΔtκS, 2, ϕ0) of the studied solutions. The results have been interpreted in terms of different solute-solvent interactions and effect of acetylsalicylic acid on hydration of amino acids. Significant effect of added acidic cosolute drug on solute-solvent interactions including hydration of amino acids has been observed. Negative standard transfer volumes in the case of l‑arginine in presence of drug validate the charge transfer to l‑arginine from drug and hence enhanced electrostriction of the solvent.

Partial molar volumes and compressibilities of α-amino acids from aqueous to aqueous-disodium tartrate solutions at T = (303.15, 308.15 and 313.15) K

Present work reports the densities (ρ) and ultrasonic velocities (u) of four α-amino acids (viz. glycine, l-proline, l-arginine and l-asparagine) in aqueous disodium tartrate (Na2Tar) (0.50, 1.00 and 1.50 mol·kg−1) solutions at T = (303.15, 308.15 and 313.15) K. Apparent molar volumes (V2, ϕ) and apparent molar isentropic compressibilities (κS, 2, ϕ) of amino acids have been calculated from density and ultrasonic velocity data respectively. Standard molar volumes (V2, ϕo) and standard molar compressibilities (κS, 2, ϕ0) were determined from the graphical fittings using standard relations and corresponding standard transfer volumes (ΔtV2, ϕo) and standard transfer compressions (ΔtκS, 2, ϕ0) were calculated. Different thermodynamic parameters have been used to explore solute-solute, solute-solvent interactions and effect of disodium tartrate salt on the hydration and electrostriction behavior of amino acids. A significant effect of added salt on the volumetric and acoustic behavior of studied amino acids through ion-ion, ion hydrophilic-hydrophilic and hydrogen bonding interactions has been observed.

Force Field Benchmark of Amino Acids: I. Hydration and Diffusion in Different Water Models.

Thermodynamic and kinetic properties are of critical importance for the applicability of computational models to biomolecules such as proteins. Here we present an extensive evaluation of the Amber ff99SB-ILDN force field for modeling of hydration and diffusion of amino acids with three-site (SPC, SPC/E, SPC/Eb, and TIP3P), four-site (TIP4P, TIP4P-Ew, and TIP4P/2005), and five-site (TIP5P and TIP5P-Ew) water models. Hydration free energies (HFEs) of neutral amino acid side chain analogues have little dependence on the water model, with a root-mean-square error (RMSE) of ∼1 kcal/mol from experimental observations. On the basis of the number of interacting sites in the water model, HFEs of charged side chains can be putatively classified into three groups, of which the group of three-site models lies between those of four- and five-site water models; for each group, the water model dependence is greatly eliminated when the solvent Galvani potential is considered. Some discrepancies in the location of the first hydration peak ( RRDF) in the ion-water radial distribution function between experimental and calculated observations were detected, such as a systematic underestimation of the acetate (Asp side chain) ion. The RMSE of calculated diffusion coefficients of amino acids from experiment increases linearly with the increasing diffusion coefficients of the solvent water models at infinite dilution. TIP3P has the fastest diffusivity, in line with literature findings, while the "FB" and "OPC" water model families as well as TIP4P/2005 perform well, within a relative error of 5%, and TIP4P/2005 yields the most accurate estimate for the water diffusion coefficient. All of the tested water models overestimate amino acid diffusion coefficients by approximately 40% (TIP4P/2005) to 200% (TIP3P). Scaling of protein-water interactions with TIP4P/2005 in the Amber ff99SBws and ff03ws force fields leads to more negative HFEs but has little influence on the diffusion of amino acids. The most recent FF/water combinations of ff14SB/OPC3, ff15ipq/SPC/Eb, and fb15/TIP3P-FB do not show obvious improvements in accuracy for the tested quantities. These findings here establish a benchmark that may aid in the development and improvement of classical force fields to accurately model protein dynamics and thermodynamics.

Компьютерное моделирование межчастичных взаимодействий в фазе анионообменника при необменной сорбции аминокислот

Исследованы межчастичные взаимодействия в фазе анионообменника АВ-17в Сl-форме при необменном поглощении биполярных ионов глицина, фенилаланина и триптофана. Квантово-химическое моделирование образующихся структур проводили с помощью программы Gaussian 03 методом гибридного функционала плотности B3LYP в базисе 6-31G++(d,p). Показано, что усложнение строения радикала аминокислоты приводит к уменьшению выигрыша энергии сорбции

Effect of infrared light on protein behavior in contact with solid surfaces

Adsorption of proteins at a solid surface affects characteristics of the surface (e.g. its biocompatibility) and functionality of the immobilized biomacromolecules. The latter is defined by the type of binding sites, protein conformation and its structural flexibility that enable functional motions to occur. Protein motions are only possible at certain level of hydration. Furthermore, water molecules act as lubricant facilitating sliding along solid surface. In this work we explore the potential of a remote physical trigger – a non-ionizing infrared radiation (IR) to affect protein-surface interactions. We report on IR-induced changes of hydrophilicity of the protein coatings on silica nanoparticles, impact of IR on monitored in-situ dynamic adsorption of proteins on silica surface and effect of IR on conformational state of adsorbed proteins. Our results indicate that IR can protect proteins from surface denaturation depending on the presence of strongly hydrated amino acid residues. Preservation of native fold results in protein coatings of higher hydrophilicity. IR can also facilitate displacement of surface active species that became adsorbed to protein apolar compartments and could otherwise promote denaturation. Apart from supporting native conformation, their removal increases protein-water interfacial tension and therefore promotes aggregation (hydrophobic attraction) of the protein-coated nanoparticles. By its ability to affect protein conformational state and interfacial characteristics (such as effective protein-water affinity) IR radiation can therefore modulate protein interactions.

Collective hydration dynamics in some amino acid solutions: A combined GHz-THz spectroscopic study.

A detailed understanding of hydration of amino acids, the building units of protein, is a key step to realize the overall solvation processes in proteins. In the present contribution, we have made a combined GHz (0.2-50) to THz (0.3-2.0) experimental spectroscopic study to investigate the dynamics of water at room temperature in the presence of different amino acids (glycine, L-serine, L-lysine, L-tryptophan, L-arginine, and L-aspartic acid). The THz absorption coefficient, α(ν), of amino acids follows a trend defined by their solvent accessible surface area. The imaginary and real dielectric constants obtained in GHz and THz regions are fitted into multiple Debye model to obtain various relaxation times. The ∼100 ps time scale obtained in the GHz frequency region is attributed to the rotational motion of the amino acids. In the THz region, we obtain ∼8 ps and ∼200 fs time scales which are related to the cooperative dynamics of H-bond network and partial rotation or sudden jump of the under-coordinated water molecules. These time scales are found to be dependent on the amino acid type and the cooperative motion is found to be dependent on both the hydrophobic as well as the hydrophilic residue of amino acids.

Amino Acid Hydration Decreases Radiation-Induced Nausea in Mice: A Pica Model.

Nausea and diarrhea are common yet inconsistent side effects of abdominal and pelvic irradiation. Their frequency, chronicity, and severity vary greatly, and the reasons for inter-subject variability are unknown. We studied the potential for radiation-induced changes in amino acid absorption and mucosal barrier function to lead to gastrointestinal toxicity. We found profound and prolonged changes in the absorption and secretion of several electrolytes and nutrients, caused by changes in transporter function, after radiation doses as low as 1 to 3 Gy. After identifying absorbed and non-absorbed amino acids, we demonstrated the role of a beneficial amino acid drink to alleviate radiation-related gastrointestinal symptoms in a mouse model.

Hydration and sorption of amino acids by an iminophosphonic ion exchanger

The interaction of glycine ions and a-alanine with an iminophosphonic Purolite S950 ion exchanger in the protonated form has been studied, and the equilibrium characteristics of ion-exchangeable and nonexchangeable sorption of amino acids have been determined. A quantitative evaluation of the degree of hydration, including the ratios of water with different energies in the phase of the exchanger in the protonated and amino acid forms, has been conducted; the changes in the Gibbs free energy and enthalpies of hydration and dehydration of PuroliteS950 have been determined. It has been found that polyampholyte in the protonated form manifests the greatest sorption capacity during sorption of bipolar amino acid ions. The amount of water of near hydration is the same for hydrogen and alanine forms of the ion exchanger; the greatest changes in the Gibbs energy are observed upon hydration of the alanine form, and those in the enthalpy are found for the hydrogen form of the polyampholyte.