Conformational heterogeneity within the Michaelis complex of lactate dehydrogenase

Hua Deng, Dung V. Vu, Keith Clinch, Ruel Desamero, R. Brian Dyer, Robert Callender

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

A series of isotope edited IR measurements, both static as well as temperature jump relaxation spectroscopy, are performed on lactate dehydrogenase (LDH) to determine the ensemble of structures available to its Michaelis complex. There clearly has been a substantial reduction in the number of states available to the pyruvate substrate (as modeled by the substrate mimic, oxamate) and NADH when bound to protein compared to dissolved in solution, as determined by the bandwidths and positions of the critical C2=O band of the bound substrate mimic and the C4-H stretch of the NADH reduced nicotinamide group. Moreover, it is found that a strong ionic bond (characterized by a signature IR band discovered in this study) is formed between the carboxyl group of bound pyruvate with (presumably) Arg171, forming a strong "anchor" within the protein matrix. However, conformational heterogeneity within the Michaelis complex is found that has an impact on both catalytic efficiency and thermodynamics of the enzyme.

Original languageEnglish (US)
Pages (from-to)7670-7678
Number of pages9
JournalJournal of Physical Chemistry B
Volume115
Issue number23
DOIs
StatePublished - Jun 16 2011

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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