Glutamate 338 is an electrostatic facilitator of C-Co bond breakage in a dynamic/electrostatic model of catalysis by ornithine aminomutase.

ABSTRACT: How cobalamin-dependent enzymes promote C-Co homolysis to initiate radical catalysis has been debated extensively. For the pyridoxal 5'-phosphate and cobalamin-dependent enzymes lysine 5,6-aminomutase and ornithine 4,5-aminomutase (OAM), large-scale re-orientation of the cobalamin-binding domain linked to C-Co bond breakage has been proposed. In these models, substrate binding triggers dynamic sampling of the B12 -binding Rossmann domain to achieve a catalytically competent 'closed' conformational state. In 'closed' conformations of OAM, Glu338 is thought to facilitate C-Co bond breakage by close association with the cobalamin adenosyl group. We investigated this using stopped-flow continuous-wave photolysis, viscosity dependence kinetic measurements, and electron paramagnetic resonance sp

SUBMITTER: Menon BR 

PROVIDER: S-EPMC4413051 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature