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A new class EC 7, Translocases, has been added to the EC list. It will be part of ENZYME from release 2018_10. Read more about EC 7 here.

ENZYME entry: EC

Accepted Name
Cyanocobalamin reductase (cyanide-eliminating).
Alternative Name(s)
Cyanocobalamin reductase.
Cyanocobalamin reductase (NADPH, cyanide-eliminating).
Cyanocobalamin reductase (NADPH; CN-eliminating).
NADPH:cyanocob(III)alamin oxidoreductase (cyanide-eliminating).
Reaction catalysed
2 cob(II)alamin-[cyanocobalamin reductase] + 2 hydrogen cyanide + NADP(+) <=> 2 cyanocob(III)alamin + 2 [cyanocobalamin reductase] + NADPH
  • The mammalian enzyme, which is cytosolic, can bind internalized cyanocobalamin and process it to cob(II)alamin by removing the upper axial ligand.
  • The product remains bound to the protein, which, together with its interacting partner MMADHC, transfers it directly to downstream enzymes involved in adenosylcobalamin and methylcobalamin biosynthesis.
  • In addition to its decyanase function, the mammalian enzyme also catalyzes an entirely different chemical reaction with alkylcobalamins, using the thiolate of glutathione for nucleophilic displacement, generating cob(I)alamin and the corresponding glutathione thioether (cf. EC
  • Formerly EC
PRIAM enzyme-specific profiles1.16.1.6
KEGG Ligand Database for Enzyme Nomenclature1.16.1.6
IUBMB Enzyme Nomenclature1.16.1.6
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