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Estimating hydration changes upon biomolecular reactions from osmotic stress, high pressure, and preferential hydration experiments.

ABSTRACT: How do we estimate, from thermodynamic measurements, the number of water molecules adsorbed or released from biomolecules as a result of a biochemical process such as binding and allosteric effects? Volumetric and osmotic stress analyses are established methods for estimating water numbers; however, these techniques often yield conflicting results. In contrast, Kirkwood-Buff theory offers a novel way to calculate excess hydration number from volumetric data, provides a quantitative condition to gauge the accuracy of osmotic stress analysis, and clarifies the relationship between osmotic and volumetric analyses. I have applied Kirkwood-Buff theory to calculate water numbers for two processes: (i) the allosteric transition of hemoglobin and (ii) the binding of camphor to cytochrome P450. I show that osmotic stress analysis may overestimate hydration number changes for these processes.

SUBMITTER: Shimizu S

PROVIDER: S-EPMC337029 | biostudies-literature | 2004 Feb

REPOSITORIES: biostudies-literature

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Estimating hydration changes upon biomolecular reactions from osmotic stress, high pressure, and preferential hydration experiments.

Shimizu Seishi S

Proceedings of the National Academy of Sciences of the United States of America 20040119 5

How do we estimate, from thermodynamic measurements, the number of water molecules adsorbed or released from biomolecules as a result of a biochemical process such as binding and allosteric effects? Volumetric and osmotic stress analyses are established methods for estimating water numbers; however, these techniques often yield conflicting results. In contrast, Kirkwood-Buff theory offers a novel way to calculate excess hydration number from volumetric data, provides a quantitative condition to ...[more]

PMID: 14732698

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