Enzyme architecture: remarkably similar transition states for triosephosphate isomerase-catalyzed reactions of the whole substrate and the substrate in pieces.

ABSTRACT: Values of (k(cat)/K(m))GAP for triosephosphate isomerase-catalyzed reactions of (R)-glyceraldehyde 3-phosphate and k(cat)/K(HPi)K(GA) for reactions of the substrate pieces glycolaldehyde and HPO3(2-) have been determined for wild-type and the following TIM mutants: I172V, I172A, L232A, and P168A (TIM from Trypanosoma brucei brucei); a 208-TGAG for 208-YGGS loop 7 replacement mutant (L7RM, TIM from chicken muscle); and, Y208T, Y208S, Y208A, Y208F and S211A (yeast TIM). A superb linear logarithmic correlation, with slope of 1.04 ± 0.03, is observed between the kinetic parameters for wild-type and most mutant enzymes, with positive deviations for L232A and L7RM. The unit slope shows that most mutations result in an identical change in the activation barriers for the catalyzed reactions of who

SUBMITTER: Zhai X 

PROVIDER: S-EPMC3985921 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature