Vitamin B12 (hydrate) (Synonyms: Cobalamin)

Vitamin B₁₂ is a water-soluble vitamin with roles in brain and nervous system functioning and blood formation through regulation of DNA synthesis, cellular metabolism, fatty acid metabolism, and amino acid metabolism.¹ It belongs to the corrinoid group of compounds, which contain a corrin macrocycle, and is produced only by certain bacteria and archaea.² Reference to vitamin B₁₂ usually encompasses a group of cobalt-containing compounds (or cobalamins), which include cyanocobalamin, hydroxocobalamin, 5'-deoxyadenosylcobalamin (AdoB₁₂), and methylcobalamin (MeB₁₂). These forms serve as cofactors in isomerase-, methyltransferase-, and dehalogenase-catalyzed reactions.³ For example, methylmalonyl coenzyme A mutase acts on AdoB₁₂ to convert methylmalonyl-CoA to succinyl-CoA, an important step before entry into the Kreb's cycle. Additionally, methionine synthase uses MeB₁₂ to transfer a methyl group from 5-methyltetrahydrofolate to homocysteine to generate tetrahydrofolate and methionine, which is important for DNA synthesis.⁴

1.Medicine, I.o.Vitamin B12Dietary reference intakes for thiamin, riboflavin, niacin, vitamin B6, folate, vitamin B12, pantothenic acid, biotin, and choline306-356(1998) 2.Moore, S.J., Lawrence, A.D., Biedendieck, R., et al.Elucidation of the anaerobic pathway for the corrin component of cobalamin (vitamin B12)Proc. Natl. Acad. Sci. USA110(37)14906-14911(2015) 3.Banerjee, R., and Ragsdale, S.W.The many faces of vitamin B12: Catalysis by cobalamin-dependent enzymesAnnual Reviews of Biochemistry72209-247(2003) 4.Ragsdale, S.W.Catalysis of methyl group transfers involving tetrahydrofolate and B12Vitamins and Hormones79293-324(2008)