Influence of Vitamin B 12 and Methionine on Levels of Folic Acid Compounds and Folate Enzymes in Rat Liver. ∗

Abstract

Summary

1. The level of methionine-forming enzyme (transmethylase) activity in rat liver is dependent on vitamin B₁₂ and is decreased by dietary methionine in much the same way as reported for chickens(10). The enzyme levels of methylene-tetrahydrofolate reductase and glutamate formiminotransfer-ase are not influenced by either vitamin B₁₂ of methionine. 2. Rats kept on a vitamin B₁₂-deficient diet low in methionine for 11 weeks show a marked drop in liver folate levels, especially higher conjugates, compared to animals supplemented with either vitamin B₁₂ or methionine, despite high folic acid content in the diet.