Methionine synthase: Difference between revisions
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MS is a B12-dependent enzyme responsible for regenerating methionine from homocysteine. MS uses vitamin B12 Cobalamin as a cofactor. The change from homocysteine to methionine is an SN2 reaction where the methyl group on N-5 from 5-me THF is donated to Cob(I)alamin forming methylcobalamin (or Me-Cob(III)alamin). This is a complex reaction as tetrahydrofolate (THF), the product, is a poor leaving group and requires the "super nucleophile", Cob(I)alamin, to carry out the reaction<ref>DOI:10.1146/annurev.biochem.72.121801.161828</ref><ref name="Kung et al">DOI: 10.1038/nature10916</ref> as a methyl carrier. | MS is a B12-dependent enzyme responsible for regenerating methionine from homocysteine. MS uses vitamin B12 Cobalamin as a cofactor. The change from homocysteine to methionine is an SN2 reaction where the methyl group on N-5 from 5-me THF is donated to Cob(I)alamin forming methylcobalamin (or Me-Cob(III)alamin). This is a complex reaction as tetrahydrofolate (THF), the product, is a poor leaving group and requires the "super nucleophile", Cob(I)alamin, to carry out the reaction<ref>DOI:10.1146/annurev.biochem.72.121801.161828</ref><ref name="Kung et al">DOI: 10.1038/nature10916</ref> as a methyl carrier. | ||
5-me THF is a product of methylenetetrahydrofolate reductase [[MTHFR]] from the folate cycle. | 5-me THF is a product of [[methylenetetrahydrofolate reductase[[ ([[MTHFR]]) from the folate cycle. | ||
== Oxidation States of Cobalamin == | == Oxidation States of Cobalamin == | ||