Mechanistic Imperatives for Deprotonation of Carbon Catalyzed by Triosephosphate Isomerase: Enzyme-Activation by Phosphite Dianion.

ABSTRACT: The mechanistic imperatives for catalysis of deprotonation of α-carbonyl carbon by triosephosphate isomerase (TIM) are discussed. There is a strong imperative to reduce the large thermodynamic barrier for deprotonation of carbon to form an enediolate reaction intermediate; and, a strong imperative for specificity in the expression of the intrinsic phosphodianion binding energy at the transition state for the enzyme-catalyzed reaction. Binding energies of 2 and 6 kcal/mol, respectively, have been determined for formation of phosphite dianion complexes to TIM and to the transition state for TIM-catalyzed deprotonation of the truncated substrate glycolaldehyde [T. L. Amyes, J. P. Richard, Biochemistry2007, 46, 5841]. We propose that the phosphite dianion binding energy, w

SUBMITTER: Zhai X 

PROVIDER: S-EPMC3979633 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature