NMR identification of transient complexes critical to adenylate kinase catalysis

被引：0

作者：

Ådén, Jörgen ^{[1
]}

Wolf-Watz, Magnus ^{[1
]}

机构：

[1] Department of Chemistry, University of Umeå, SE-901 87 Umeå, Sweden

来源：

Journal of the American Chemical Society | 2007年 / 129卷 / 45期

关键词：

A fundamental question in protein chemistry is how the native energy landscape of enzymes enables efficient catalysis of chemical reactions. Adenylate kinase is a small monomeric enzyme that catalyzes the reversible conversion of AMP and ATP into two ADP molecules. Previous structural studies have revealed that substrate binding is accompanied by large rate-limiting spatial displacements of both the ATP and AMP binding motifs. In this report a solution-state NMR approach was used to probe the native energy landscape of adenylate kinase in its free form; in complex with its natural substrates; and in the presence of a tight binding inhibitor. Binding of ATP induces a dynamic equilibrium in which the ATP binding motif populates both the open and the closed conformations with almost equal populations. A similar scenario is observed for AMP binding; which induces an equilibrium between open and closed conformations of the AMP binding motif. These ATP- and AMP-bound structural ensembles represent complexes that exist transiently during catalysis. Simultaneous binding of AMP and ATP is required to force both substrate binding motifs to close cooperatively. In addition; a previously unknown unidirectional energetic coupling between the ATP and AMP binding sites was discovered. On the basis of these and previous results; we propose that adenylate kinase belongs to a group of enzymes whose substrates act to shift pre-existing equilibria toward catalytically active states. © 2007 American Chemical Society;

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摘要：

Journal article (JA)

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页码：14003 / 14012