Gerlits Oksana, Wymore Troy, Das Amit, Shen Chen-Hsiang, Parks Jerry M, Smith Jeremy C, Weiss Kevin L, Keen David A, Blakeley Matthew P, Louis John M, Langan Paul, Weber Irene T, Kovalevsky Andrey
Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
Angew Chem Int Ed Engl. 2016 Apr 11;55(16):4924-7. doi: 10.1002/anie.201509989. Epub 2016 Mar 9.
Neutron crystallography was used to directly locate two protons before and after a pH-induced two-proton transfer between catalytic aspartic acid residues and the hydroxy group of the bound clinical drug darunavir, located in the catalytic site of enzyme HIV-1 protease. The two-proton transfer is triggered by electrostatic effects arising from protonation state changes of surface residues far from the active site. The mechanism and pH effect are supported by quantum mechanics/molecular mechanics (QM/MM) calculations. The low-pH proton configuration in the catalytic site is deemed critical for the catalytic action of this enzyme and may apply more generally to other aspartic proteases. Neutrons therefore represent a superb probe to obtain structural details for proton transfer reactions in biological systems at a truly atomic level.
利用中子晶体学直接定位了两个质子，这两个质子位于pH诱导的两个质子在催化天冬氨酸残基与结合在酶HIV-1蛋白酶催化位点的临床药物达芦那韦羟基之间转移之前和之后。两个质子的转移是由远离活性位点的表面残基质子化状态变化产生的静电效应触发的。该机制和pH效应得到了量子力学/分子力学（QM/MM）计算的支持。催化位点的低pH质子构型被认为对该酶的催化作用至关重要，并且可能更普遍地适用于其他天冬氨酸蛋白酶。因此，中子是在真正的原子水平上获取生物系统中质子转移反应结构细节的极佳探针。
