Set of water-soluble factors belonging to group B, cobalamin is considered the largest and most structurally complex vitamin of the entire category.
; the only organisms capable of producing it are some bacteria and the unicellular organisms of the Archaea Kingdom.Herbivores introduce bacteria directly with the plants they consume; these then reach the digestive system of animals, proliferate and integrate into the permanent intestinal flora, producing vitamin B12 from the inside.
The term "cobalamin" derives from cobalt, a rare chemical element with the symbol "Co". The various forms of cobalamin are characterized by a corrin nucleus similar to porphyrin - which in fact contains a cobalt atom - linked to a benzimidazolyl nucleotide, and a group of variable residues (R).
In cyanocobalamin the residue R is cyanide; in hydroxocobalamin it is a hydroxyl group. Cyanocobalamin and hydroxocobalamin can be converted into one of the two cobalaminic coenzymes active in human metabolism: adenosylcobalamin (AdoB12) and methylcobalamin (MeB12). AdoB12 has a 5 group. "-deoxyadenosyl attached to the cobalt atom in the nucleus of the molecule; MeB12 has a methyl group in that location. These active enzymatic cofactors perform their function in the mitochondria and cell cytosol."
Bacterial fermentation creates AdoB12 and MeB12, which are converted to cyanocobalamin by adding potassium cyanide in the presence of sodium nitrite and heat. Once consumed, cyanocobalamin is converted into biologically active AdoB12 and MeB12.
