Department of Chemistry and Howard Hughes Medical Institute, The University of Chicago, Chicago, Illinois 60637, USA.
J Phys Chem B. 2010 Nov 25;114(46):15113-8. doi: 10.1021/jp102820e. Epub 2010 Nov 3.
This paper describes a model system to characterize the rate enhancement that stems from localization of an enzyme with its substrate. The approach is based on a self-assembled monolayer that presents a substrate for the serine esterase cutinase along with a peptide ligand for an SH2 adaptor domain. The monolayer is treated with a fusion protein of cutinase and the SH2 domain, and the rate for the interfacial reaction is monitored using cyclic voltammetry. The rate is approximately 30-fold greater for monolayers that present the ligand for the SH2 domain than for those that omit the ligand. The rate enhancement is due to the interaction of the adaptor domain with the immobilized ligand. Further, the rate enhancement increases with the densities of both the ligand and the substrate. This example provides a well-defined model system for quantitatively assessing the magnitude of rate enhancement that is possible with colocalization of an enzyme with its substrate and may be particularly significant for understanding the signaling events that rely on enzyme localization at the cell membrane.
本文描述了一个模型系统，用于描述酶与其底物定位所带来的反应速率增强。该方法基于自组装单分子层，该单分子层呈现丝氨酸酯酶角质酶的底物以及 SH2 衔接子结构域的肽配体。用角质酶和 SH2 结构域的融合蛋白处理单层，并使用循环伏安法监测界面反应的速率。呈现 SH2 结构域配体的单层的反应速率比不呈现配体的单层的反应速率大约快 30 倍。这种速率增强是由于衔接子结构域与固定化配体的相互作用。此外，速率增强随配体和底物的密度增加而增加。该示例提供了一个明确的模型系统，用于定量评估酶与其底物共定位可能带来的反应速率增强的幅度，对于理解依赖于酶在细胞膜上定位的信号事件可能特别重要。
