Hwang J K, Warshel A
Biochemistry. 1987 May 19;26(10):2669-73. doi: 10.1021/bi00384a003.
The catalytic free energy and binding free energies of the native and the Asn-155----Thr, Asn-155----Leu, and Asn-155----Ala mutants of subtilisin are calculated by the empirical valence bond method and a free energy perturbation method. Two simple procedures are used; one "mutates" the substrate, and the other "mutates" the enzyme. The calculated changes in free energies (delta delta G not equal to cat and delta delta Gbind) between the mutant and native enzymes are within 1 kcal/mol of the corresponding observed values. This indicates that we are approaching a quantitative structure-function correlation. The calculated changes in catalytic free energies are almost entirely due to the electrostatic interaction between the enzyme-water system and the charges of the reacting system. This supports the idea that the electrostatic free energy associated with the changes of charges of the reacting system is the key factor in enzyme catalysis.
通过经验价键法和自由能微扰法计算了枯草杆菌蛋白酶天然型以及天冬酰胺-155→苏氨酸、天冬酰胺-155→亮氨酸和天冬酰胺-155→丙氨酸突变体的催化自由能和结合自由能。使用了两种简单的方法：一种是“突变”底物，另一种是“突变”酶。突变体和天然酶之间计算得到的自由能变化（ΔΔGcat和ΔΔGbind）与相应的观测值相差在1千卡/摩尔以内。这表明我们正在接近定量的结构-功能相关性。计算得到的催化自由能变化几乎完全归因于酶-水体系与反应体系电荷之间的静电相互作用。这支持了这样一种观点，即与反应体系电荷变化相关的静电自由能是酶催化的关键因素。
