Direct evidence of catalytic heterogeneity in lactate dehydrogenase by temperature jump infrared spectroscopy.

ABSTRACT: Protein conformational heterogeneity and dynamics are known to play an important role in enzyme catalysis, but their influence has been difficult to observe directly. We have studied the effects of heterogeneity in the catalytic reaction of pig heart lactate dehydrogenase using isotope edited infrared spectroscopy, laser-induced temperature jump relaxation, and kinetic modeling. The isotope edited infrared spectrum reveals the presence of multiple reactive conformations of pyruvate bound to the enzyme, with three major reactive populations having substrate C2 carbonyl stretches at 1686, 1679, and 1674 cm(-1), respectively. The temperature jump relaxation measurements and kinetic modeling indicate that these substates form a heterogeneous branched reaction pathway, and each substate catalyz

SUBMITTER: Reddish MJ 

PROVIDER: S-EPMC4167064 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature