Methylcobalamin (mecobalamin, MeCbl, or MeB12) is a cobalamin, a form of vitamin B12. It differs from cyanocobalamin in that the cyano group at the cobalt is replaced with a methyl group.[1] Methylcobalamin features an octahedral cobalt(III) centre and can be obtained as bright red crystals.[2] From the perspective of coordination chemistry, methylcobalamin is notable as a rare example of a compound that contains metal–alkyl bonds. Nickel–methyl intermediates have been proposed for the final step of methanogenesis.
Methylcobalamin is equivalent physiologically to vitamin B12,[3] and can be used to prevent or treat pathology arising from a lack of vitamin B12 intake (vitamin B12 deficiency).
Methylcobalamin is also used in the treatment of peripheral neuropathy, diabetic neuropathy, and as a preliminary treatment for amyotrophic lateral sclerosis.[4]
Methylcobalamin that is ingested is not used directly as a cofactor, but is first converted by MMACHC into cob(II)alamin. Cob(II)alamin is then later converted into the other two forms, adenosylcobalamin and methylcobalamin for use as cofactors. That is, methylcobalamin is first dealkylated and then regenerated.[5][6][7]
According to one author, it is important to treat vitamin B12 deficiency with hydroxocobalamin or cyanocobalamin or a combination of adenosylcobalamin and methylcobalamin, and not methylcobalamin alone.[8]
^McDowell LR (2000). Vitamins in animal and human nutrition. Wiley. ISBN 978-0813826301. Retrieved 28 January 2018 – via Booksgoogle.com.
^Cite error: The named reference MechB12 was invoked but never defined (see the help page).
^Sil A, Kumar H, Mondal RD, Anand SS, Ghosal A, Datta A, Sawant SV, Kapatkar V, Kadhe G, Rao S (July 2018). "A randomized, open labeled study comparing the serum levels of cobalamin after three doses of 500 mcg vs. a single dose methylcobalamin of 1500 mcg in patients with peripheral neuropathy". The Korean Journal of Pain. 31 (3): 183–190. doi:10.3344/kjp.2018.31.3.183. PMC 6037815. PMID 30013732.
^"Eisai Submits New Drug Application for Mecobalamin Ultra-High Dose Preparation as Treatment for Amyotrophic Lateral Sclerosis in Japan" (PDF). Eisai.com. Retrieved 28 January 2018.
^Kim J, Hannibal L, Gherasim C, Jacobsen DW, Banerjee R (November 2009). "A human vitamin B12 trafficking protein uses glutathione transferase activity for processing alkylcobalamins". The Journal of Biological Chemistry. 284 (48): 33418–33424. doi:10.1074/jbc.M109.057877. PMC 2785186. PMID 19801555.
^Hannibal L, Kim J, Brasch NE, Wang S, Rosenblatt DS, Banerjee R, Jacobsen DW (August 2009). "Processing of alkylcobalamins in mammalian cells: A role for the MMACHC (cblC) gene product". Molecular Genetics and Metabolism. 97 (4): 260–266. doi:10.1016/j.ymgme.2009.04.005. PMC 2709701. PMID 19447654.
^Froese DS, Gravel RA (November 2010). "Genetic disorders of vitamin B₁₂ metabolism: eight complementation groups–eight genes". Expert Reviews in Molecular Medicine. 12: e37. doi:10.1017/S1462399410001651. PMC 2995210. PMID 21114891.
^Thakkar K, Billa G (January 2015). "Treatment of vitamin B12 deficiency – Methylcobalamine? Cyancobalamine? Hydroxocobalamin? – clearing the confusion". European Journal of Clinical Nutrition. 69 (1): 1–2. doi:10.1038/ejcn.2014.165. PMID 25117994.
Methylcobalamin (mecobalamin, MeCbl, or MeB12) is a cobalamin, a form of vitamin B12. It differs from cyanocobalamin in that the cyano group at the cobalt...
degradation. Methylcobalamin is also offered as a dietary supplement. There is no advantage to the use of adenosylcobalamin or methylcobalamin forms for...
prepared by this method include the naturally occurring coenzymes methylcobalamin and cobamamide, and other cobalamins that do not occur naturally, such...
known as coenzyme B12, cobamamide, and dibencozide, is, along with methylcobalamin (MeCbl), one of the biologically active forms of vitamin B12. Adenosylcobalamin...
contains L-methylfolate (as Metafolin, a calcium salt of vitamin B9), methylcobalamin (vitamin B12) and pyridoxal 5'-phosphate (vitamin B6). It is a vitamin...
Homocystinuria or HCU is an inherited disorder of the metabolism of the amino acid methionine due to a deficiency of cystathionine beta synthase or methionine...
group gives rise to the four most commonly known cobalamins: CNCbl, methylcobalamin, 5-deoxyadenosylcobalamin, and OHCbl. In the serum, hydroxocobalamin...
contains 5.635 mg of folate as L-methylfolate, 1 mg of vitamin B12 as methylcobalamin, 50 mg of vitamin B2 as riboflavin, and 5 mg of vitamin B6 as pyridoxine...
It is routinely produced by various enzymes of the radical SAM and methylcobalamin varieties. The reactivity of a methyl group depends on the adjacent...
anti-inflammatory drugs (NSAIDs), prostaglandin-based drugs, gabapentin, and methylcobalamin. However, the quality of evidence supporting their use is not high...
cobalamin-independent: Plants have both, animals depend on the methylcobalamin-dependent form. In methylcobalamin-dependent forms of the enzyme, the reaction proceeds...
extracts, tablets or powder. Vitamin B12, specifically in the form of methylcobalamin, has been identified in Chlorella vulgaris. "Chlorella vulgaris". NCBI...
absorption. It can be treated with injections of replacement vitamin B12 (methylcobalamin, hydroxocobalamin or cyanocobalamin). Achlorhydria is another autoimmune...
trimethylaluminium (Me3Al). A naturally occurring organometallic complex is methylcobalamin (a form of Vitamin B12), which contains a cobalt-methyl bond. This...
ion and is usually found in one of two biologically active forms: methylcobalamin and adenosylcobalamin. Most prokaryotes, as well as animals, have cobalamin-dependent...
infancy and pregnancy. Vitamin B12 Cobalamins Commonly cyanocobalamin or methylcobalamin in vitamin supplements. A coenzyme involved in the metabolism of all...
convert these elements into volatile compounds, it is thought that methylcobalamin (vitamin B12) alkylates these elements to create the dimethyls. It...
and proteins include the hydrogenases, FeMoco in nitrogenase, and methylcobalamin. These naturally occurring organometallic compounds. This area is more...
reported that some microbes can methylate polonium by the action of methylcobalamin. This is similar to the way in which mercury, selenium, and tellurium...
Pretek-GM, Rejusite, Renerve-P, Safyvit-PR, and Vitcobin-P, Voltanerv with Methylcobalamin and ALA by Cogentrix Pharma. "Pregabalin - Drugs.com". www.drugs.com...
monoxide dehydrogenase. The coupling of the methyl group (provided by methylcobalamin) and CO is catalyzed by acetyl-CoA synthase. The global reduction reaction...
thymidylate synthase. Methyl-THF converts vitamin B12 to methyl-B12 (methylcobalamin). Methyl-B12 converts homocysteine, in a reaction catalyzed by homocysteine...
; Dilshad, P.; Vaidyanathan, G.; Thakur, M.S.; Sarada, R. (2015). "Methylcobalamin – a form of vitamin B12 identified and characterised in Chlorella vulgaris"...
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