Determination of pre-steady-state rate constants on the Escherichia coli pyruvate dehydrogenase complex reveals that loop movement controls the rate-limiting step.

ABSTRACT: Spectroscopic identification and characterization of covalent and noncovalent intermediates on large enzyme complexes is an exciting and challenging area of modern enzymology. The Escherichia coli pyruvate dehydrogenase multienzyme complex (PDHc), consisting of multiple copies of enzymic components and coenzymes, performs the oxidative decarboxylation of pyruvate to acetyl-CoA and is central to carbon metabolism linking glycolysis to the Krebs cycle. On the basis of earlier studies, we hypothesized that the dynamic regions of the E1p component, which undergo a disorder-order transition upon substrate binding to thiamin diphosphate (ThDP), play a critical role in modulation of the catalytic cycle of PDHc. To test our hypothesis, we kinetically characterized ThDP-bound covalent intermediates

SUBMITTER: Balakrishnan A 

PROVIDER: S-EPMC3498582 | biostudies-literature | 2012 Nov

REPOSITORIES: biostudies-literature