Eaton W A, Henry E R, Hofrichter J
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.
Proc Natl Acad Sci U S A. 1991 May 15;88(10):4472-5. doi: 10.1073/pnas.88.10.4472.
The transition state for the R in equilibrium with T quaternary conformational change of hemoglobin has thermodynamic properties much closer to those of the R conformation than to those of the T conformation. This finding is based on a comparison of activation and equilibrium enthalpy and entropy changes and on the observation of a linear free energy relationship between quaternary rate and equilibrium constants. A previous theoretical study [Janin, J. & Wodak, S. J. (1985) Biopolymers 24, 509-526], using a highly simplified energy function, suggests that the R-like transition state is the result of a reaction pathway with the maximum buried surface area between alpha beta dimers.
与血红蛋白四级构象变化的T处于平衡状态的R的过渡态，其热力学性质与R构象的热力学性质更为接近，而与T构象的热力学性质相差较大。这一发现基于对活化和平衡焓变及熵变的比较，以及对四级反应速率和平衡常数之间线性自由能关系的观察。之前一项使用高度简化能量函数的理论研究[贾宁，J. & 沃达克，S. J.（1985年）《生物聚合物》24，509 - 526]表明，类R过渡态是αβ二聚体之间具有最大埋藏表面积的反应途径的结果。
