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ENZYME entry: EC

Accepted Name
corrinoid adenosyltransferase.
Alternative Name(s)
aquacob(I)alamin adenosyltransferase.
aquocob(I)alamin vitamin B12s adenosyltransferase.
ATP:cob(I)alamin Cobeta-adenosyltransferase.
ATP:corrinoid adenosyltransferase.
cob(I)alamin adenosyltransferase.
cob(I)yrinic acid a,c-diamide adenosyltransferase.
Reaction catalysed
  • 2 ATP + 2 cob(II)alamin + reduced [electron-transfer flavoprotein] <=> 2 adenosylcob(III)alamin + 3 H(+) + oxidized [electron-transfer flavoprotein] + 2 triphosphate
  • 2 ATP + 2 cob(II)yrinate a,c diamide + reduced [electron-transfer flavoprotein] <=> 2 adenosylcob(III)yrinate a,c-diamide + 3 H(+) + oxidized [electron-transfer flavoprotein] + 2 triphosphate
  • The corrinoid adenosylation pathway comprises three steps: (i) reduction of Co(III) 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 adenosylcobalamin de novo biosynthesis and salvage), the pduO gene (involved in (S)-propane-1,2-diol utilization), and the eutT gene (involved in ethanolamine utilization).
  • Since EutT hydrolyzes triphosphate during catalysis, it is classified as a separate enzyme.
  • The mammalian enzyme belongs to the PduO type.
  • The enzyme can act on other corrinoids, such as cob(II)inamide.
  • Formerly EC
PRIAM enzyme-specific profiles2.5.1.17
KEGG Ligand Database for Enzyme Nomenclature2.5.1.17
IUBMB Enzyme Nomenclature2.5.1.17
MEDLINEFind literature relating to
Rhea expert-curated reactions2.5.1.17
P31570, BTUR_SALTY;  Q9I472, COBO_PSEAE;  P29930, COBO_SINSX;  
O34899, PDUO_BACSU;  P64804, PDUO_MYCBO;  P53523, PDUO_MYCLE;  

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