Hydration of α-chymotrypsin: Excess partial enthalpies of water and enzyme

Sirotkin, Vladimir A.; Khadiullina, Aigul V.

doi:10.1016/j.tca.2011.02.030

Cited by 5 publications

(11 citation statements)

References 27 publications

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“…This contrasts with what is contained in the excess functions (for example, V E ), the first derivative quantities, which provide the respective global averages. As can be concluded from our work, the published partial enthalpies , and the partial volumes obtained in this work (Figures and ) show similar profiles and a glasslike transition in the w 1 range from 0.06 to 0.5. Figure shows the excess function of mixing, V E .…”

Section: Resultssupporting

confidence: 85%

“…The hydration of proteins is a phenomenon of considerable fundamental importance and practical interest. It is well-known that water bound to proteins (hydration or biological water) plays a crucial role in determining their stability, dynamics, and functions. − On the other hand, there are essential differences between the hydration water surrounding the protein and bulk water. − This means that a characterization of protein hydration requires elucidating the effects of both the protein on water and water on the protein.…”

Section: Introductionmentioning

confidence: 99%

“…A novel method has recently been proposed for simultaneously studying the partial enthalpies of water and the proteins. , This method is based on the analysis of the thermodynamic functions of mixing. In this work, we applied this method for the simultaneous monitoring of the partial volumes of water and the proteins in the entire range of water contents.…”

Section: Introductionmentioning

confidence: 99%

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Hydration of Proteins: Excess Partial Volumes of Water and Proteins

2012

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High precision densitometry was applied to study the hydration of proteins. The hydration process was analyzed by the simultaneous monitoring of the excess partial volumes of water and the proteins in the entire range of water content. Five unrelated proteins (lysozyme, chymotrypsinogen A, ovalbumin, human serum albumin, and β-lactoglobulin) were used as models. The obtained data were compared with the excess partial enthalpies of water and the proteins. It was shown that the excess partial quantities are very sensitive to the changes in the state of water and proteins. At the lowest water weight fractions (w(1)), the changes of the excess functions can mainly be attributed to water addition. A transition from the glassy to the flexible state of the proteins is accompanied by significant changes in the excess partial quantities of water and the proteins. This transition appears at a water weight fraction of 0.06 when charged groups of proteins are covered. Excess partial quantities reach their fully hydrated values at w(1) > 0.5 when coverage of both polar and weakly interacting surface elements is complete. At the highest water contents, water addition has no significant effect on the excess quantities. At w(1) > 0.5, changes in the excess functions can solely be attributed to changes in the state of the proteins.

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Section: Resultssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydration of Proteins: Excess Partial Volumes of Water and Proteins

2012

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“…Lines are shown to guide the eye. (b) Enthalpy of adsorption for the rigid and flexible crystals compared with experimental measurements on bovine serum albumin, α-chymotrypsin, and lysozyme …”

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confidence: 99%

“…This quantity contains information regarding the adsorption energetics and can be measured experimentally using calorimetry or calculated from isotherm data. Figure b shows the simulated results along with experimental data for three different proteins. − The enthalpy of vaporization, Δ H vap , for the SPC/E model and real water have been subtracted from the simulated and experimental results, respectively, so that the data in Figure b approach zero for a dilute protein solution.…”

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confidence: 99%

Computer Simulation of Water Sorption on Flexible Protein Crystals

Palmer

Debenedetti

2012

J. Phys. Chem. Lett.

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The first simulation study of water sorption on a flexible protein crystal is presented, along with a new computational approach for calculating sorption isotherms on compliant materials. The flexible ubiquitin crystal examined in the study exhibits appreciable sorption-induced swelling during fluid uptake, similar to that reported in experiments on protein powders. A completely rigid ubiquitin crystal is also examined to investigate the impact that this swelling behavior has on water sorption. The water isotherms for the flexible crystal exhibit Type II-like behavior with sorption hysteresis, which is consistent with experimental measurements on protein powders. Both of these behaviors, however, are absent in the rigid crystal, indicating that modeling flexibility is crucial for predicting water sorption behavior in protein systems. Changes in the enthalpy of adsorption, specific volume, and internal protein fluctuations that occur during sorption in the flexible crystal are also shown to compare favorably with experiment.

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