Loop dynamics and ligand binding kinetics in the reaction catalyzed by the Yersinia protein tyrosine phosphatase

Mazdak Khajehpour, Li Wu, Sijiu Liu, Nick Zhadin, Zhong Yin Zhang, Robert Callender

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Abstract

The Yersinia protein tyrosine phosphatase (YopH) contains a loop of ten amino acids (the WPD loop) that covers the entrance of the active site of the enzyme during substrate binding. In this work the substrate mimicking competitive inhibitor p-nitrocatechol sulfate (PNC) is used as a probe of the active site. The dynamics of the WPD loop was determined by subjecting an equilibrated system containing YopH, PNC, and YopH bound to PNC to a laser induced temperature jump, and subsequently following the change in equilibrium due to the perturbation. Using this methodology the dynamics associated with substrate binding in YopH have been determined. These results indicate that substrate binding is coupled to the WPD loop motion, and WPD loop dynamics occur in the sub-millisecond time scale. The significance of these dynamic results is interpreted in terms of the catalytic cycle of the enzyme.

Original languageEnglish (US)
Pages (from-to)4370-4378
Number of pages9
JournalBiochemistry
Volume46
Issue number14
DOIs
Publication statusPublished - Apr 10 2007

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ASJC Scopus subject areas

  • Biochemistry

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