Spectroscopic and Computational Insights into the Mechanism of Cofactor Cobalt-Carbon Bond Homolysis by the Adenosylcobalamin-Dependent Enzyme Ethanolamine Ammonia-Lyase.

ABSTRACT: The adenosylcobalamin (AdoCbl)-dependent enzyme ethanolamine ammonia-lyase (EAL) catalyzes the conversion of ethanolamine to acetaldehyde and ammonia. As is the case for all AdoCbl-dependent isomerases, the catalytic cycle of EAL is initiated by homolytic cleavage of the cofactor's Co-C bond, producing Co^IIcobalamin (Co^IICbl) and an adenosyl radical that serves to abstract a hydrogen atom from the substrate. Remarkably, in the presence of substrate, the rate of Co-C bond homolysis of enzyme-bound AdoCbl is increased by 12 orders of magnitude. For Class I AdoCbl-dependent isomerases, an important contribution to this rate acceleration stems from a stabilization of the Co^IICbl posthomolysis product by the axially coordinated histidine residue that displaces t

SUBMITTER: Elmendorf LD 

PROVIDER: S-EPMC12281503 | biostudies-literature | 2025 Jan

REPOSITORIES: biostudies-literature