Apparent molar isentropic compressions and expansions of solutions

Blandamer, Michael J.; Davis, Michaël I.; Douhéret, Gérard; Reis, João Carlos R.

doi:10.1039/a908547e

Cited by 92 publications

(71 citation statements)

References 30 publications

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“…However, the underlying assumption is oversimplified because this equation does not take the thermal expansion of a bulk solvent into consideration. The relationship between the two compressibilities for a solute in solution is expressed rigorously as follows (Blandamer et al 2001;Taulier and Chalikian 2002): The difference between the two compressibilities increases with decreasing temperature, which contradicts the theoretical expectation that it should decrease to zero around 4 ı C, where the solvent expansion is negligible (˛o D 0). The origin of these discrepancies cannot be explained at present because the experimentally observedˇT o andˇs o values may involve some unknown contributions in addition to large experimental errors (greater than 5 %).…”

Section: Difference Between Adiabatic and Isothermal Compressibilitiesmentioning

confidence: 92%

Volume and Compressibility of Proteins

Gekko

2015

Subcellular Biochemistry

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The partial specific (or molar) volume, expansibility, and compressibility of a protein are fundamental thermodynamic quantities for characterizing its structure in solution. We review the definitions, measurements, and implications of these volumetric quantities in relation to protein structural biology. The partial specific volumes under constant molality (isomolal) and chemical potential (isopotential) conditions of the cosolvent (multicomponent systems) are explained in terms of preferential solvent interactions relevant to the solubility and stability of proteins. The partial expansibility is briefly discussed in terms of the effects of temperature on protein-solvent interactions (hydration) and internal packing defects (cavities). We discuss the compressibility-structure-function relationships of proteins based on analyses of the correlations between the partial adiabatic compressibilities and the structures or functions of various globular proteins (including mutants), focusing on the roles of the internal cavities in structural fluctuations. The volume and compressibility changes associated with various conformational transitions are also discussed in terms of the changes in hydration and cavities in order to elucidate the nonnative structures and the transition mechanisms, especially those associated with pressure denaturation.

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Section: Difference Between Adiabatic and Isothermal Compressibilitiesmentioning

confidence: 92%

Volume and Compressibility of Proteins

Gekko

2015

Subcellular Biochemistry

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“…68 Due to a small value of a 0 and a large value of c P0 of water-based solvents, the difference between K T and K S in aqueous solutions is not large. Therefore, we use Eq.…”

Section: Urea Affinity For Various Functional Groupsmentioning

confidence: 99%

Urea interactions with protein groups: A volumetric study

2010

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We determined the partial molar volumes and adiabatic compressibilities of N-acetyl amino acid amides, N-acetyl amino acid methylamides, N-acetyl amino acids, and short oligoglycines as a function of urea concentration. We analyze these data within the framework of a statistical thermodynamic formalism to determine the association constants for the reaction in which urea binds to the glycyl unit and each of the naturally occurring amino acid side chains replacing two waters of hydration. Our determined association constants, k, range from 0.04 to 0.39 M. We derive a general equation that links k with changes in free energy, DeltaGtr, accompanying the transfer of functional groups from water to urea. In this equation, DeltaGtr is the sum of a change in the free energy of cavity formation, DeltaDeltaGC, and the differential free energy of solute-solvent interactions, DeltaDeltaGI, in urea and water. The observed range of affinity coefficients, k, corresponds to the values of DeltaDeltaGI ranging from highly favorable to slightly unfavorable. Taken together, our data support a direct interaction model in which urea denatures a protein by concerted action via favorable interactions with a wide range of protein groups. Our derived equation linking k to DeltaGtr suggests that DeltaDeltaGI and, hence, the net transfer free energy, DeltaGtr, are both strongly influenced by the concentration of a solute used in the experiment. We emphasize the need to exercise caution when two solutes differing in solubility are compared to determine the DeltaGtr contribution of a particular functional group.

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“…For the peptides glyproalaalagly and glyphealagly the values obtained for the a 2 coefficient were not statistically significant. The values of κ S were used to calculate the apparent molar isentropic compression, K S,φ , which is defined by the relation [13,38] …”

Section: Resultsmentioning

confidence: 99%

Partial Molar Isentropic Compressions of Some Tetra- and Pentapeptides in Aqueous Solution: Implications for Group Additivity Schemes for Unfolded Proteins

Hedwig

Høiland

2012

J Solution Chem

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Sound speeds have been measured for aqueous solutions of five tetrapeptides and five pentapeptides at T = 298.15 K. The partial molar isentropic compressions at infinite dilution, K • S,2 , were derived for the peptides using conventional methods. The results were compared with those calculated using group additivity methods, with the amino acid sidechain contributions derived using K • S,2 data reported previously for some tripeptides of sequence gly-X-gly, where X represents an amino acid, and also for some N -acetyl amino acid amides. The tripeptides are the preferred model compounds for the estimation of the side-chain contributions to K • S,2 of a polypeptide. Our study also confirms that simple group additivity schemes are not feasible for the estimation of K • S,2 values for polypeptides and unfolded proteins.

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Apparent molar isentropic compressions and expansions of solutions

Cited by 92 publications

References 30 publications

Volume and Compressibility of Proteins

Volume and Compressibility of Proteins

Urea interactions with protein groups: A volumetric study

Partial Molar Isentropic Compressions of Some Tetra- and Pentapeptides in Aqueous Solution: Implications for Group Additivity Schemes for Unfolded Proteins

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