|Aquocob(I)alamin vitamin B12s adenosyltransferase.|
|Cob(I)yrinic acid a,c-diamide adenosyltransferase.|
- 2 ATP + 2 cob(II)alamin + a reduced flavoprotein <=> 2 triphosphate + 2 adenosylcob(III)alamin + an oxidized flavoprotein
- 2 ATP + 2 cob(II)yrinic acid a,c-diamide + a reduced flavoprotein <=> 2 triphosphate + 2 adenosylcob(III)yrinic acid a,c-diamide + an oxidized flavoprotein
- 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.
|PRIAM enzyme-specific profiles||184.108.40.206|
|KEGG Ligand Database for Enzyme Nomenclature||220.127.116.11|
|IUBMB Enzyme Nomenclature||18.104.22.168|
|MEDLINE||Find literature relating to 22.214.171.124|
|Rhea expert-curated reactions||126.96.36.199|
|P45515, ATR_CITFR; ||P0A9H6, BTUR_ECOL6; ||P0A9H5, BTUR_ECOLI; |
|P31570, BTUR_SALTY; ||Q9I472, COBO_PSEAE; ||P29930, COBO_SINSX; |
|O34899, PDUO_BACSU; ||P64804, PDUO_MYCBO; ||P53523, PDUO_MYCLE; |
|P9WP98, PDUO_MYCTO; ||P9WP99, PDUO_MYCTU; |