A link between hinge-bending domain motions and the temperature dependence of catalysis in 3-isopropylmalate dehydrogenase.

ABSTRACT: Enzyme function depends on specific conformational motions. We show that the temperature dependence of enzyme kinetic parameters can provide insight into these functionally relevant motions. While investigating the catalytic properties of IPMDH from Escherichia coli, we found that its catalytic efficiency (k(cat)/K(M,IPM)) for the substrate IPM has an unusual temperature dependence, showing a local minimum at approximately 35 degrees C. In search of an explanation, we measured the individual constants k(cat) and K(M,IPM) as a function of temperature, and found that the van 't Hoff plot of K(M,IPM) shows sigmoid-like transition in the 20-40 degrees C temperature range. By means of various measurements including hydrogen-deuterium exchange and fluorescence resonance energy transfer, we showe

SUBMITTER: Hajdu I 

PROVIDER: S-EPMC2712055 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature