Methionine synthase: Difference between revisions
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[[Image:Methionine synthase domains.gif]] | [[Image:Methionine synthase domains.gif]] | ||
The full structure of MS has yet to be | The full structure of MS has yet to be determined. | ||
Shown here is the <scene name='90/907471/Superposition/7'>theoretical prediction</scene> of the structure by the alphafold algorithm, with experimental structures of the N-terminal 2 domains as well as of the C-terminal 2 domins superposed. | Shown here is the <scene name='90/907471/Superposition/7'>theoretical prediction</scene> of the structure by the alphafold algorithm, with experimental structures of the N-terminal 2 domains as well as of the C-terminal 2 domins superposed. | ||
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=== Cobalamin activation === | === Cobalamin activation === | ||
<scene name='90/907471/B12_activation_w_sah/1'> | Every 2000 or so cycles, cobalamin needs to be <scene name='90/907471/B12_activation_w_sah/1'>reactivated</scene> through methylation by S-adenosyl methionine (SAM). To determine the structure of the reactivation conformation, the mutant H759G was used. This mutation maximises the fraction of enzyme with the B12 domain in the cap-off conformation bound to the activation domain. The approach of the B12 domain and the activation domain has to be carefully regulated because methylating homocysteine with methyl groups from S-adenosyl methionine results in a futile cycle. Thus, this step should be reserved to rescue B12 out of the +2 cobalt oxidation state, and then methylation of homocysteine using a methyl group from 5-me THF resumes. | ||
=== Cap domain === | === Cap domain === | ||
