B12

Vitamin B12, or cobalamin, is a water-soluble vitamin that acts as an essential coenzyme in human metabolism. Methylcobalamin is its active coenzyme form, the one used in the reaction that regenerates methionine from homocysteine. It is supplied here as an analytical-grade reference material for laboratory research use only.

No. Unlike most of this catalogue, B12 is a vitamin, not a peptide — a cobalt-containing molecule built on a corrin ring. It is included because it is a common analytical reference standard and is frequently studied alongside these compounds.

B12 serves as a coenzyme in two reactions: methylcobalamin supports methionine synthase, which converts homocysteine back to methionine and keeps the cell's methylation chemistry running, and a second form supports a mitochondrial step in fat and amino-acid breakdown. The methylation route is the one usually invoked to explain why nerve tissue is affected early when B12 is scarce.

Chiefly deficiency — how it presents, how it is detected and how it is corrected — plus peripheral nerve function, homocysteine and methylation, and red-blood-cell formation. Most trials test correcting a shortfall rather than adding more where levels are already adequate, and the neuropathy results specifically are mixed and modest.

Cold and, above all, dark — methylcobalamin degrades in light, so amber vials or foil are standard. Keep the lyophilized powder refrigerated or frozen, refrigerate a reconstituted solution at about 2-8 °C, and avoid repeated freeze-thaw cycles. Fading of its deep red colour suggests degradation.