Methionine synthase

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Contents 1 Methionine synthase 2 Structural highlights 3 Vitamin B-12 4 Oxidation States of Cobalamin 5 Relevance 6 References

Methionine synthase

spinqualitylabelsall models B-12 dependent fragment of E. coli methionine synthase with Cobalt (in pink) Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image This page is being worked on during the Spring 2022 semester. EC: 2.1.1.13 PDB ID: 1K7Y - cobalamin, 1K98 - AdoMet complex 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, and we get it from our diet first in the form of homocysteine. The change from homocysteine to methionine is an SN2 reaction where the methyl group from methyltetrahydrofolate (MTHF), located on N-5, is donated. MTHF is a product of MTHFR. This is a complex reaction as the product, tetrahydrofolate, is a poor leaving group, thus requiring a "supernucleophile" with a protein-bound B-12 vitamin Cobalamin as the methyl carrier.

Structural highlights

Methionine synthase (MetH) is a B12-dependent enzyme that methylates homocysteine to regenerate methionine. The has yet to be determined but we understand it contains 4 domains of B12 cobalamin (in pink), methyltetrahydrofolate (blue), homocysteine (yellow), and SAH (as part of the SAM cycle; in red). Each domain with an important function required for catalytic and reactivation cycles.

Vitamin B-12

Oxidation States of Cobalamin

Relevance

Methionine deficiency can result in diseases such as birth abnormalities.

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References

^[1]

1. ↑ Barra L, Fontenelle C, Ermel G, Trautwetter A, Walker GC, Blanco C. Interrelations between glycine betaine catabolism and methionine biosynthesis in Sinorhizobium meliloti strain 102F34. J Bacteriol. 2006 Oct;188(20):7195-204. doi: 10.1128/JB.00208-06. PMID:17015658 doi:http://dx.doi.org/10.1128/JB.00208-06