title: Cobalamin-dependent and cobamide-dependent methyltransferases.
abstract: Methyltransferases that employ cobalamin cofactors, or their analogs the cobamides, as intermediates in catalysis of methyl transfer play vital roles in energy generation in anaerobic unicellular organisms. In a broader range of organisms they are involved in the conversion of homocysteine to methionine. Although the individual methyl transfer reactions catalyzed are simple S(N)2 displacements, the required change in coordination at the cobalt of the cobalamin or cobamide cofactors and the lability of the reduced Co(+1) intermediates introduces the necessity for complex conformational changes during the catalytic cycle. Recent spectroscopic and structural studies on several of these methyltransferases have helped to reveal the strategies by which these conformational changes are facilitated and controlled.
authors.affiliation: Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2216, USA. rmatthew@umich.edu
authors.forename: Rowena G
authors.initials: RG
authors.lastname: Matthews
authors.forename: Markos
authors.initials: M
authors.lastname: Koutmos
authors.forename: Supratim
authors.initials: S
authors.lastname: Datta
mesh_terms: D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase / Q000737:chemistry / Q000378:metabolism; D000214:Acyl Coenzyme A / Q000378:metabolism; D000818:Animals; D003038:Cobamides / Q000737:chemistry* / Q000378:metabolism; D045728:Corrinoids / Q000737:chemistry / Q000378:metabolism; D006639:Histidine / Q000737:chemistry / Q000378:metabolism; D007501:Iron / Q000737:chemistry; D008024:Ligands; D008780:Methyltransferases / Q000737:chemistry* / Q000378:metabolism; D009097:Multienzyme Complexes / Q000737:chemistry; D013455:Sulfur / Q000737:chemistry; D014805:Vitamin B 12 / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000214:Acyl Coenzyme A; D003038:Cobamides; D045728:Corrinoids; D008024:Ligands; D009097:Multienzyme Complexes; D006639:Histidine; D013455:Sulfur; D007501:Iron; D008780:Methyltransferases; C036890:methanol-2-mercaptoethanesulfonic acid methyltransferase; D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; D014805:Vitamin B 12