has role R-cob(III)alamin cobalamins cofactor methylcobalamin methylcob(III)alamin CHEBI:28115 CHEBI:25291 DrugBank:DB03614 COMe:MOL000085 CHEBI:48831 Methylcobalamin CHEBI:6869 mecobalamin KEGG:D03246 MeCbl PDBeChem:COB Coalpha-[alpha-(5,6-dimethylbenzimidazolyl)]-Cobeta-methylcobamide CO-METHYLCOBALAMIN methylcobalamin KEGG:C06453 mouse metabolite human metabolite