What role does Cobalamin (B12) play in metabolism?

Cobalamin, also known as vitamin B12, plays a crucial role in the conversion of homocysteine to methionine, which is a vital process in amino acid metabolism. This reaction is catalyzed by the enzyme methionine synthase, which requires cobalamin as a cofactor.

Methionine itself is an essential amino acid that serves as a precursor to other important biomolecules, including S-adenosylmethionine (SAM), a universal methyl donor involved in methylation reactions throughout the body, affecting DNA, proteins, and lipids.

The inability to convert homocysteine to methionine due to cobalamin deficiency leads to an accumulation of homocysteine, which is associated with a higher risk of cardiovascular disease and other health issues. This highlights the importance of cobalamin in maintaining proper homocysteine levels and overall metabolic health.

The other options presented do not accurately reflect the primary metabolic role of cobalamin. While carbohydrate metabolism, fatty acid oxidation, and protein synthesis are vital processes, they are not directly linked to the specific functions of vitamin B12 in the body. Therefore, the correct choice emphasizes the unique and critical function of cobalamin in methylation