Spectroscopic studies of the Salmonella enterica adenosyltransferase enzyme SeCobA: molecular-level insight into the mechanism of substrate Cob(II)alamin activation.

ABSTRACT: CobA from Salmonella enterica (SeCobA) is a member of the family of ATP:Co(I)rrinoid adenosyltransferase (ACAT) enzymes that participate in the biosynthesis of adenosylcobalamin by catalyzing the transfer of the adenosyl group from an ATP molecule to a reactive Co(I)rrinoid species transiently generated in the enzyme active site. This reaction is thermodynamically challenging, as the reduction potential of the Co(II)rrinoid precursor in solution is far more negative than that of available reducing agents in the cell (e.g., flavodoxin), precluding nonenzymic reduction to the Co(I) oxidation state. However, in the active sites of ACATs, the Co(II)/Co(I) redox potential is increased by >250 mV via the formation of a unique four-coordinate (4c) Co(II)rrinoid species. In the case of the SeCobA

SUBMITTER: Pallares IG 

PROVIDER: S-EPMC4278676 | biostudies-literature | 2014 Dec

REPOSITORIES: biostudies-literature