A fundamental question in protein chemistry is how the native energy landscape of enzymes enables efficient catalysis of chemical reactions. @entity1920 kinase is a small monomeric enzyme that catalyzes the reversible conversion of @entity860 and @entity855 into two @entity857 molecules. Previous structural studies have revealed that substrate binding is accompanied by large rate-limiting spatial displacements of both the @entity855 and @entity860 binding motifs. In this report a solution-state NMR approach was used to probe the native energy landscape of @entity1920 kinase in its free form, in complex with its natural substrates, and in the presence of a tight binding inhibitor. Binding of @entity855 induces a dynamic equilibrium in which the @entity855 binding motif populates both the open and the closed conformations with almost equal populations. A similar scenario is observed for @entity860 binding, which induces an equilibrium between open and closed conformations of the @entity860 binding motif. These @entity855 - and @entity860 -bound structural ensembles represent complexes that exist transiently during catalysis. Simultaneous binding of @entity860 and @entity855 is required to force both substrate binding motifs to close cooperatively. In addition, a previously unknown unidirectional energetic coupling between the @entity855 and @entity860 binding sites was discovered. On the basis of these and previous results, we propose that @entity1920 kinase belongs to a group of enzymes whose substrates act to shift pre-existing equilibria toward catalytically active states.

NMR identification of transient complexes critical to XXXX kinase catalysis.

@entity860 :: ('MESH:D000249', 'Chemical') :: ['AMP'] @entity857 :: ('MESH:D000244', 'Chemical') :: ['ADP'] @entity1920 :: ('CHEBI:16027', 'Chemical') :: ['Adenylate', 'adenylate'] @entity855 :: ('MESH:D000255', 'Chemical') :: ['ATP']
@entity1920 :: (CHEBI:16027,Chemical) :: ['adenylate']
