ENTHALPIC AND ENTROPIC CONTRIBUTIONS OF WATER-MOLECULES TO THE FUNCTIONAL T -] R TRANSITION OF HUMAN HEMOGLOBIN IN SOLUTION

被引:17
作者
BULONE, D [1 ]
PALMAVITTORELLI, MB [1 ]
PALMA, MU [1 ]
机构
[1] UNIV PALERMO,DEPT PHYS,I-90123 PALERMO,ITALY
关键词
D O I
10.1002/qua.560420518
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Generalized solvent-mediated forces contribute to free energy at the functional T --> R transition of human hemoglobin A (HbA). Their contribution is here sorted out quantitatively in both its enthalpic and entropic parts, along with the average number of water molecules involved. The latter (about 75 waters in average) must be considered together with HbA as one statistically defined functional unit for oxygen transport. Their configurations are expected to undergo frequent structural rearrangements. Lifetimes of statistically relevant configurations do not need to (although, of course, they may) exceed by more than a factor 5 the normal H-bond lifetimes of the pure solvent. Compared to the bare protein, the "functional unit" here evidenced for the first time involves a larger, higher dimensionality region of the phase space. The study allows a microscopic view of solvent-mediated generalized forces and evidences their qualitative and quantitative relevance to biomacromolecular function and stability.
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页码:1427 / 1437
页数:11
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