Methionine synthase: Difference between revisions
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Addlt ref 2<ref>DOI:10.1073/pnas.1133218100</ref> | Addlt ref 2<ref>DOI:10.1073/pnas.1133218100</ref> | ||
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'''Methionine synthase''' (MS; EC: 2.1.1.13) is the enzyme in [[one-carbon metabolism]] linking the folate cycle and the methionine cycle. MS catalyzes the transfer of a methyl group from 5-methyltetrahydrofolate (5- me THF) to homocysteine, resulting in the formation of methionine. Methionine is an essential amino acid required by our bodies for healthy cell and tissue growth. It is essential as it is not naturally derived in our bodies. As it is used as a methyl donor in the form of S-adenosylmethionine, the resulting homocysteine is recyled to form methionine again. | '''Methionine synthase''' (MS; EC: 2.1.1.13) is the enzyme in [[one-carbon metabolism]] linking the folate cycle and the methionine cycle. MS catalyzes the transfer of a methyl group from 5-methyltetrahydrofolate (5- me THF) to homocysteine, resulting in the formation of methionine. Methionine is an essential amino acid required by our bodies for healthy cell and tissue growth. It is essential as it is not naturally derived in our bodies. As it is used as a methyl donor in the form of S-adenosylmethionine, the resulting homocysteine is recyled to form methionine again. | ||
==Function== | ==Function== | ||
MS is a B12-dependent enzyme responsible for regenerating methionine from homocysteine and uses vitamin B12 Cobalamin as a cofactor. The change from homocysteine to methionine is an SN2 reaction, as seen above, where the methyl group on N-5 from 5-me THF, is donated. 5-me THF is a product of methylenetetrahydrofolate reductase [[MTHFR]] from the folate cycle. This is a complex reaction as tetrahydrofolate (THF), the product, is a poor leaving group and requires a "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 and uses vitamin B12 Cobalamin as a cofactor. The change from homocysteine to methionine is an SN2 reaction, as seen above, where the methyl group on N-5 from 5-me THF, is donated. 5-me THF is a product of methylenetetrahydrofolate reductase [[MTHFR]] from the folate cycle. This is a complex reaction as tetrahydrofolate (THF), the product, is a poor leaving group and requires a "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. | ||
