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ARS Home » Pacific West Area » Davis, California » Western Human Nutrition Research Center » Obesity and Metabolism Research » Research » Publications at this Location » Publication #276000
Title: Vitamin B-12

Author
item Allen, Lindsay - A

Submitted to: Advances in Nutrition
Publication Type: Review Article
Publication Acceptance Date: 6/20/2012
Publication Date: 6/20/2012
Citation: Allen, L.H. 2012. Vitamin B-12. Advances in Nutrition. 3:54-55.

Interpretive Summary:

Technical Abstract: Vitamin B-12 is a cofactor for 2 enzymes. In the cytoplasm, methionine synthase requires vitamin B-12 in the form of methylcobalamin and catalyzes the conversion of homocysteine to methionine by transfer of a methyl group from methyltetrahydrofolate.This enzyme links the methylation pathway through synthesis of the methyl donor S-adenosyl methionine and the pathway in which purine and pyrimidine are synthesized via generation of tetrahydrofolate. In the form of 59-deoxyadenosylcobalamin, vitamin B-12 is also required for the mitochondrial enzyme methylmalonyl CoA mutase, which converts methylmalonyl CoA to succinyl CoA, a step in the oxidation of odd-chain fatty acids and catabolism of ketogenic amino acids. Thus, vitamin B-12 is important for DNA synthesis, regenerating methionine for protein synthesis and methylation, and preventing homocysteine accumulation (1).