Lerch Hans-Philipp, Rigler Rudolf, Mikhailov Alexander S
Abteilung Physikalische Chemie, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany.
Proc Natl Acad Sci U S A. 2005 Aug 2;102(31):10807-12. doi: 10.1073/pnas.0504995102. Epub 2005 Jul 26.
Reexamining experimental data of single-molecule fluorescence correlation spectroscopy for cholesterol oxidase, we find that the existing Michaelis-Menten models with dynamical disorder cannot explain strong correlations between subsequent turnover cycles revealed in the diagonal feature in the joint statistical distribution of adjacent "on" times of this enzyme. We suggest that functional conformational motions representing ordered sequences of transitions between a set of conformational substates are involved, along with equilibrium conformational fluctuations in the turnover cycle of cholesterol oxidase. A two-channel model of single-enzyme dynamics, including a slow functional conformational motion in one of the channels, is proposed that allows us to reproduce such strong correlations.
重新审视胆固醇氧化酶的单分子荧光相关光谱实验数据时，我们发现现有的带有动态无序的米氏模型无法解释该酶相邻“开启”时间的联合统计分布对角特征中所揭示的后续周转循环之间的强相关性。我们认为，胆固醇氧化酶的周转循环中涉及到代表一组构象亚态之间有序转变序列的功能性构象运动以及平衡构象波动。提出了一种单酶动力学的双通道模型，其中一个通道包含缓慢的功能性构象运动，该模型能够重现这种强相关性。
