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ENZYME entry: EC

Accepted Name
corrinoid adenosyltransferase EutT
Reaction catalysed
2 ATP + 2 cob(II)alamin + 2 H2O + reduced [electron-transfer flavoprotein] <=> 2 adenosylcob(III)alamin + 2 diphosphate + 3 H(+) + oxidized [electron-transfer flavoprotein] + 2 phosphate
  • The corrinoid adenosylation pathway comprises three steps.
  • (i) reduction of Co(III) within the corrinoid to Co(II) by a one- electron transfer. This can occur non-enzymically in the presence of dihydroflavin nucleotides or reduced flavoproteins.
  • (ii) Co(II) is bound by corrinoid adenosyltransferase, resulting in displacement of the lower axial ligand by an aromatic residue. The reduction potential of the 4-coordinate Co(II) intermediate is raised by ~250 mV compared with the free compound, bringing it to within physiological range.
  • This is followed by a second single-electron transfer from either free dihydroflavins or the reduced flavin cofactor of flavoproteins, resulting in reduction to Co(I).
  • (iii) the Co(I) conducts a nucleophilic attack on the adenosyl moiety of ATP, resulting in transfer of the deoxyadenosyl group and oxidation of the cobalt atom to Co(III) state.
  • Three types of corrinoid adenosyltransferases, not related by sequence, have been described. In the anaerobic bacterium Salmonella enterica they are encoded by the cobA gene (a housekeeping enzyme involved in both the de novo biosynthesis and the salvage of adenosylcobalamin), the pduO gene (involved in (S)-propane-1,2-diol utilization), and the eutT gene (involved in ethanolamine utilization).
  • The first two types, which produce triphosphate, are classified as EC, while the EutT type hydrolyzes triphosphate to diphosphate and phosphate during catalysis and is thus classified separately.
PRIAM enzyme-specific profiles2.5.1.154
KEGG Ligand Database for Enzyme Nomenclature2.5.1.154
IUBMB Enzyme Nomenclature2.5.1.154
MEDLINEFind literature relating to
Rhea expert-curated reactions2.5.1.154

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