Methylcobalamin (also called mecobalamin) is one of the two coenzyme forms of vitamin B12. Like all cobalamins, it has a cobalt atom at the center of a corrin ring; in methylcobalamin, a methyl group ...
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About Vitamin B12 (Methylcobalamin)
Methylcobalamin (also called mecobalamin) is one of the two coenzyme forms of vitamin B12. Like all cobalamins, it has a cobalt atom at the center of a corrin ring; in methylcobalamin, a methyl group is bound directly to that cobalt.[4] Pepitiva supplies it as an injectable research solution in 10 mL vials, stored refrigerated.
Is methylcobalamin methylated B12?
Yes. The name describes exactly that: methyl-cobalamin. Other forms carry a different group on the cobalt: cyanocobalamin (a cyano group), hydroxocobalamin (a hydroxyl group) and adenosylcobalamin (a 5'-deoxyadenosyl group).[1] These forms have different molecular weights and CAS numbers: methylcobalamin is 1344.4 g/mol (CAS 13422-55-4), while cyanocobalamin is 1355.4 g/mol (CAS 68-19-9).[4][5]
For research use only.
Mechanism of Action
Cofactor roles
The body uses two coenzyme forms of B12:
Methylcobalamin is the cofactor of methionine synthase, the enzyme that converts homocysteine to methionine.
Adenosylcobalamin is the cofactor of methylmalonyl-CoA mutase.[1]
The structure of the cobalamin-binding region of methionine synthase, solved by X-ray crystallography, showed how the enzyme recognizes the cofactor.[2]
Intracellular processing
All supplemental forms are taken up by the same transport proteins. Inside the cell, the chaperone MMACHC removes the upper group (cyano, methyl or adenosyl) to produce a common cobalamin intermediate, from which the cell makes its own methylcobalamin and adenosylcobalamin. On this basis, a 2015 review concluded that supplementing methylcobalamin is unlikely to be advantageous over cyanocobalamin for preventing or treating deficiency.[1]
Research Applications
Research highlights
Ultrahigh-dose methylcobalamin in early ALS (phase 3, 2022): in 130 patients in Japan, functional decline on the ALSFRS-R scale at 16 weeks was 1.97 points smaller with methylcobalamin than with placebo, with similar adverse event rates.[3]
Neuropathy: methylcobalamin has been studied, alone and in combination, in diabetic peripheral neuropathy models and trials.[6]
Laboratory research applications
One-carbon metabolism: methionine synthase activity and homocysteine remethylation.
Cobalamin processing: MMACHC-dependent conversion between cobalamin forms.
Neuroscience models: peripheral nerve and motor neuron studies.
Metabolic research: often studied alongside NAD+ and the lipotropic MIC blend.
Storage
Keep the solution refrigerated at 2 to 8 °C.
Frequently Asked Questions
Is methylcobalamin methylated B12?
Yes. Methylcobalamin is vitamin B12 with a methyl group bound to the central cobalt atom. It is one of the two coenzyme forms of B12.
What is mecobalamin?
Mecobalamin is another name for methylcobalamin.
What is the difference between methylcobalamin and cyanocobalamin?
Cyanocobalamin carries a cyano group on the cobalt instead of a methyl group, and it has a different molecular weight (1355.4 g/mol) and CAS number (68-19-9). Inside cells, both are converted to the same intermediate before the cell makes its active coenzymes.
What does methylcobalamin do?
It is the cofactor of methionine synthase, which converts homocysteine to methionine. The other coenzyme form, adenosylcobalamin, serves methylmalonyl-CoA mutase.
What is the CAS number and molecular weight of methylcobalamin?
CAS 13422-55-4. Molecular formula C63H91CoN13O14P, molecular weight 1344.4 g/mol (PubChem).
How should it be stored?
Keep the solution refrigerated at 2 to 8 °C.
Scientific References
Obeid R, Fedosov SN, Nexo E. Cobalamin coenzyme forms are not likely to be superior to cyano- and hydroxyl-cobalamin in prevention or treatment of cobalamin deficiency. Mol Nutr Food Res. 2015;59(7):1364-1372. PubMed
Drennan CL, Matthews RG, Ludwig ML. Cobalamin-dependent methionine synthase: the structure of a methylcobalamin-binding fragment and implications for other B12-dependent enzymes. Curr Opin Struct Biol. 1994;4(6):919-929. PubMed
Oki R, Izumi Y, Fujita K, et al. Efficacy and Safety of Ultrahigh-Dose Methylcobalamin in Early-Stage Amyotrophic Lateral Sclerosis: A Randomized Clinical Trial. JAMA Neurol. 2022;79(6):575-583. PubMed
PubChem. Methylcobalamin, CID 10898559: C63H91CoN13O14P, 1344.4 g/mol, CAS 13422-55-4. Source
PubChem. Cyanocobalamin, CID 166596686: C63H88CoN14O14P, 1355.4 g/mol, CAS 68-19-9. Source
Xu Q, Pan J, Yu J, et al. Meta-analysis of methylcobalamin alone and in combination with lipoic acid in patients with diabetic peripheral neuropathy. Diabetes Res Clin Pract. 2013;101(2):99-105. PubMed
Sources are peer-reviewed publications indexed in PubMed and trial registrations on ClinicalTrials.gov. Each citation was checked against its PubMed record.
For research use only. Not for human consumption.
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