Methionine synthase: Difference between revisions
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'''Cob(I)alamin''': Cobalt in the +1 oxidation state is nicknamed the "super nucleophile" as its high energy is required to carry out the complex SN2 reaction of breaking the bond between THF and the methyl group, in the catalytic cycle. | '''Cob(I)alamin''': Cobalt in the +1 oxidation state is nicknamed the "super nucleophile" as its high energy is required to carry out the complex SN2 reaction of breaking the bond between THF and the methyl group, in the catalytic cycle. | ||
'''Co(III)alamin''': Cobalt in +3 oxidation state occurs when His 759 | '''Co(III)alamin''': Cobalt in +3 oxidation state occurs when His 759 displaces the dimethylbenzimidazole (DMB) ligand to allow for the methyl to be accepted by Cob(I)alamin, forming Me-Cob(III)alamin. | ||
'''Cob(II)alamin''': Cob(I)alamin is highly reactive towards oxygen so occasionally under aerobic conditions, Cob(I)alamin will undergo oxidation leading to an inactive Cob(II)alamin enzyme in the +2 oxidation state. This is regulated by reductive methylation by using Flavodoxin as an electron donor to reactivate Cob(I)alamin, and subsequently regenerates Me-Cob(III)alamin with a methyl being donated from SAM<ref>DOI:10.1073/pnas.1133218100</ref>. | '''Cob(II)alamin''': Cob(I)alamin is highly reactive towards oxygen so occasionally under aerobic conditions, Cob(I)alamin will undergo oxidation leading to an inactive Cob(II)alamin enzyme in the +2 oxidation state. This is regulated by reductive methylation by using Flavodoxin as an electron donor to reactivate Cob(I)alamin, and subsequently regenerates Me-Cob(III)alamin with a methyl being donated from SAM<ref>DOI:10.1073/pnas.1133218100</ref>. | ||
