Vitamin B12, also known as cobalamin, is an essential coenzyme in several enzymatic reactions. It is crucial for the conversion of homocysteine to methionine, a reaction catalyzed by methionine synthase. Methionine is vital for the synthesis of S-adenosylmethionine (SAM), a key methyl donor in numerous methylation reactions, including DNA methylation. A deficiency in vitamin B12 can hinder these catalytic processes, leading to impaired DNA synthesis and the development of megaloblastic anemia.
