Methionine synthase: Difference between revisions

Line 74:

DMB, in the lower ligand of the <scene name='90/907471/Bindingdomain2/1'>B12 binding domain</scene> is displaced from the Cobalt by a Histidine residue to be 'uncapped' to form Me-Cob(III)alamin<ref>DOI:10.1146/annurev.biochem.72.121801.161828</ref>.

~~== Cobalamin activation ==~~

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 ==

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</jmolRadioGroup>

</jmol>

== Cobalamin activation ==

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.

</StructureSection>

Methionine synthase: Difference between revisions

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@@ Line 74: / Line 74: @@
 DMB, in the lower ligand of the <scene name='90/907471/Bindingdomain2/1'>B12 binding domain</scene> is displaced from the Cobalt by a Histidine residue to be 'uncapped' to form Me-Cob(III)alamin<ref>DOI:10.1146/annurev.biochem.72.121801.161828</ref>.
-== Cobalamin activation ==
-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 ==
@@ Line 110: / Line 105: @@
     </jmolRadioGroup>
 </jmol>
+== Cobalamin activation ==
+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.
 </StructureSection>