期刊
ANALYTICAL CHEMISTRY
卷 89, 期 24, 页码 13326-13333出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.analchem.7b03506
关键词
-
资金
- Natural Sciences and Engineering Research Council of Canada [217080-2013]
It is believed that enzyme catalysis is facilitated by conformational dynamics of the protein scaffold that surrounds the active site, yet the exact nature of catalytically relevant protein motions remains largely unknown. Hydrogen/deuterium exchange (HDX) mass spectrometry (MS) reports on backbone H-bond fluctuations. HDX/MS thus represents a promising avenue for probing the relationship between enzyme dynamics and catalysis. A seemingly straightforward strategy for such studies involves comparative measurements during substrate turnover and in the resting state. We examined the feasibility of this approach using rabbit muscle pyruvate kinase (rM1-PK) which catalyzes the conversion of phosphoenolpyruvate and Mg-ADP to pyruvate and Mg-ATP. HDX/MS revealed that catalytically active rM1-PK undergoes significant rigidification in the active site. This finding is counterintuitive, considering the purported correlation between dynamics and catalysis. Interestingly, virtually the same rigidification was seen upon exposing rMl-PK to substrates or products in the absence of turnover. These data imply that the active site dynamics during turnover are dominated by protein-ligand binding interactions. These interactions stabilize H-bonds in the vicinity of the active site, thereby masking subtle dynamic features that might be uniquely associated with catalysis. Our data uncover an inherent problem with side-by-side turnover/resting state measurements, i.e., the difficulty to design a suitable reference state against which the working enzyme can be compared. Comparative HDX/MS experiments on enzyme dynamics should therefore be interpreted with caution.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据