A primary hydrogen–deuterium isotope effect observed at the single-molecule level
作者:Siran Lu、Wen-Wu Li、Dvir Rotem、Ellina Mikhailova、Hagan Bayley
DOI:10.1038/nchem.821
日期:2010.11
The covalent chemistry of reactants tethered within a single protein pore can be monitored by observing the time-dependence of ionic current flow through the pore, which responds to bond making and breaking in individual reactant molecules. Here we use this ânanoreactorâ approach to examine the reaction of a quinone with a thiol to form a substituted hydroquinone by reductive 1,4-Michael addition. Remarkably, a primary hydrogenâdeuterium isotope effect is readily detected at the single-molecule level during prototropic rearrangement of an initial adduct. The observation of individual reaction intermediates allows the measurement of an isotope effect whether or not the step involved is rate limiting, which would not be the case in an ensemble measurement. When anchored inside a protein pore, the bond-making and bond-breaking events of a single reacting molecule can be detected by alterations in current flow. This approach is used to detect a hydrogenâdeuterium kinetic isotope effect. The single-molecule measurements provide information not available from experiments on an ensemble system.
通过观察离子电流流经孔隙的时间依赖性,可以监测单个蛋白质孔隙内反应物的共价化学反应。在这里,我们利用这种 "纳米反应器 "方法研究了醌与硫醇通过还原性1,4-迈克尔加成反应生成取代对苯二酚的过程。值得注意的是,在初始加合物的原向重排过程中,很容易在单分子水平上检测到原氢氘同位素效应。通过观察单个反应中间体,可以测量出同位素效应,而不管所涉及的步骤是否限制速率,这在整体测量中是不存在的。当锚定在蛋白质孔内时,单个反应分子的成键和断键事件可通过电流变化进行检测。这种方法可用于检测氢氘动力学同位素效应。单分子测量所提供的信息是对一个集合系统进行实验所无法获得的。