B-12

B-12 (vitamin B₁₂, cobalamin) is a cobalt-centered corrinoid that cells convert into two cofactor forms: methylcobalamin for methionine synthase and adenosylcobalamin for methylmalonyl-CoA mutase. That places it at the junction of folate one-carbon metabolism, S-adenosylmethionine production and mitochondrial branched-chain amino acid catabolism. Researchers have studied cobalamin enzyme structures, transcobalamin receptor-mediated uptake in cultured cells, and peripheral nerve changes in cobalamin-deficient rats. Research Market supplies B-12 with lot identity and purity data on the certificate of analysis. It is sold strictly for laboratory research use.

Chemical structure and identification

• Compound class: Cobalt-containing corrinoid (cobalamin)
• Chemical form: The product listing does not state which cobalamin (for example cyanocobalamin or methylcobalamin); the form is reported on the batch certificate of analysis
• Form: Supplied in a sealed research vial
• Analytical methods: Identity and purity data reported on the batch certificate of analysis

Research applications

• Cofactor biochemistry: Reviewed for cobalamin absorption and processing into adenosyl- and methylcobalamin, the cofactors of methylmalonyl-CoA mutase and methionine synthase, and the intersection with folate one-carbon metabolism [1]
• Enzyme structure: Reviewed from X-ray structures showing that cobalamin’s dimethylbenzimidazole ligand is displaced by a histidine residue when it binds methionine synthase and methylmalonyl-CoA mutase [2]
• Cellular uptake: In cultured cells, siRNA knockdown of the transcobalamin receptor TCblR/CD320 reduced uptake of transcobalamin-bound cobalamin, increased doubling time and decreased proliferation [3]
• Deficiency models: In rats made cobalamin-deficient by total gastrectomy or diet, intramyelin and endoneural edema, slower nerve conduction and lower myelinated fiber density were reported, with reversal after cobalamin administration in gastrectomized rats [4]

Reference citations

1. Froese D.S. et al. (2019). Vitamin B₁₂, folate, and the methionine remethylation cycle-biochemistry, pathways, and regulation. J Inherit Metab Dis, 42(4):673–685. PMID 30693532 · DOI
2. Ludwig M.L. et al. (1997). Structure-based perspectives on B12-dependent enzymes. Annu Rev Biochem, 66:269–313. PMID 9242908 · DOI
3. Lai S.C. et al. (2011). Down-regulation of transcobalamin receptor TCblR/CD320 by siRNA inhibits cobalamin uptake and proliferation of cells in culture. Exp Cell Res, 317(11):1603–1607. PMID 21377459 · DOI
4. Tredici G. et al. (1998). Polyneuropathy due to cobalamin deficiency in the rat. J Neurol Sci, 156(1):18–29. PMID 9559982 · DOI

Literature summaries describe published preclinical research and are not claims about this product’s effects in humans or animals.