Vitamin B12 (B12)

Vitamin B12 (cobalamin) is a water-soluble vitamin that is unique for containing cobalt at the center of its large, complex corrin ring structure. It is essential for normal nervous system function, red blood cell formation, and DNA synthesis. The human body uses two active forms—methylcobalamin and adenosylcobalamin—to serve as cofactors for methionine synthase (important for methylation of DNA, RNA, proteins, and lipids) and L-methylmalonyl-CoA mutase (involved in energy production and metabolism of odd-chain fatty acids and some amino acids)[1][4][6]. Vitamin B12 is supplied by animal-derived foods and is absorbed in the distal ileum via a complex process involving intrinsic factor and specialized receptors. Deficiency leads to megaloblastic anemia and neurological disorders. Although used as a therapeutic drug to treat deficiency, vitamin B12 itself is not a molecular therapeutic target (such as a receptor, enzyme, or transporter), but instead a required nutrient and prosthetic group for certain enzymes[2][4][6].

Other names

CobalaminCyanocobalaminMethylcobalaminAdenosylcobalaminHydroxycobalaminExtrinsic factor

Functions as a cofactor for methionine synthase and L-methylmalonyl-CoA mutase; critical for conversion of homocysteine to methionine and for metabolism of certain fatty acids and amino acids[2][4][6]