Uncovering the Role of Key Active-Site Side Chains in Catalysis: An Extended Bronsted Relationship for Substrate Deprotonation Catalyzed by Wild-Type and Variants of Triosephosphate Isomerase.

ABSTRACT: We report results of detailed empirical valence bond simulations that model the effect of several amino acid substitutions on the thermodynamic (ΔG°) and kinetic activation (ΔG^⧧) barriers to deprotonation of dihydroxyacetone phosphate (DHAP) and d-glyceraldehyde 3-phosphate (GAP) bound to wild-type triosephosphate isomerase (TIM), as well as to the K12G, E97A, E97D, E97Q, K12G/E97A, I170A, L230A, I170A/L230A, and P166A variants of this enzyme. The EVB simulations model the observed effect of the P166A mutation on protein structure. The E97A, E97Q, and E97D mutations of the conserved E97 side chain result in ≤1.0 kcal mol^-1 decreases in the activation barrier for substrate deprotonation. The agreement between experimental and computed activation barriers

SUBMITTER: Kulkarni YS 

PROVIDER: S-EPMC7032883 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature