探究过氧化氢酶在有无磁场下的构象动力学  

Probing conformational kinetics of catalase with and without magnetic field by single-entity collision electrochemistry

作　　者：丁清丹 孙泽晖 马巍 Qingdan Ding;Zehui Sun;Wei Ma(Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering,Feringa Nobel Prize Scientist Joint Research Center,Frontiers Science Center for Materiobiology and Dynamic Chemistry,School of Chemistry and Molecular Engineering,East China University of Science and Technology,Shanghai 200237,China)

机构地区：[1]Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering,Feringa Nobel Prize Scientist Joint Research Center,Frontiers Science Center for Materiobiology and Dynamic Chemistry,School of Chemistry and Molecular Engineering,East China University of Science and Technology,Shanghai 200237,China

出　　处：《Science Bulletin》2023年第21期2564-2573,M0005,共11页科学通报（英文版）

基　　金：supported by the Major Research Project of China(92061108);the National Natural Science Foundation of China(22272052);Shanghai Municipal Science and Technology Major Project(2018SHZDZX03);Xiamen University Opening Project of PCOSS(201901);sponsored by National Ten Thousand Talent Program for Young Top-notch Talent。

摘　　要：酶分子的构象变化对其催化活性至关重要,但这些自发的、非同步的构象波动很难通过整体系综的测量方法获得.本文采用无标记的单体碰撞电化学方法实时追踪了单个过氧化氢酶分子在有无磁场下双氧水降解过程中酶活性的动态波动.利用高分辨电化学测量,探测单个过氧化氢酶分子在碳纳米电极上的电化学信号,解析观察到的3种不同特征电流轨迹,获取了酶分子在催化反应过程中亚毫秒时间尺度上构象变化.在施加磁场条件下,由于过氧化氢酶的铁活性中心构象运动受到限制,只观测到单个过氧化氢酶分子呈现出几乎一致的单峰信号.进一步,通过将高分辨电化学信号和多物理场模拟模型相结合研究了过氧化氢酶分子在有无磁场条件下的催化反应动力学信息,并计算了过氧化氢酶催化反应的最大催化速率和构象转变速率.该工作为现有的单分子酶学引入了一种新方法,有助于深入理解酶的催化反应机制.The conformational motions of enzymes are crucial for their catalytic activities,but these fluctuations are usually spontaneous and unsynchronized and thus difficult to obtain from ensemble-averaged measurements.Here,we employ label-free single-entity electrochemical measurements to monitor in real time the fluctuating enzymatic behavior of single catalase molecules toward the degradation of hydrogen peroxide.By probing the electrochemical signals of single catalase molecules at a carbon nanoelectrode,we were able to observe three distinct current traces that could be attributed to conformational changes on the sub-millisecond timescale.Whereas,nearly uniform single long peaks were observed for single catalase molecules under a moderate magnetic field due to the restricted conformational changes of catalase.By combining high-resolution current signals with a multiphysics simulation model,we studied the catalytic kinetics of catalase with and without a magnetic field,and further estimated the maximum catalytic rate and conformational transition rate.This work introduces a new complementary approach to existing single-molecule enzymology,giving further insight into the enzymatic reaction mechanism.

关 键 词：催化反应过程 活性中心 过氧化氢酶 酶催化反应 催化反应动力学 电化学测量 系综 构象变化 

分 类 号：Q55[生物学—生物化学]