title: Physiological importance of the heterodisulfide of coenzyme M and 7-mercaptoheptanoylthreonine phosphate in the reduction of carbon dioxide to methane in Methanobacterium.
abstract: The heterodisulfide of the two coenzymes 2-mercaptoethanesulfonic acid (coenzyme M, HS-CoM) and N-(7-mercaptoheptanoyl)threonine O3-phosphate (HS-HTP) increased the rate of CO2 reduction to methane by cell extracts 42-fold. The stimulation resulted from activation of the initial step of methanogenesis, the production of formylmethanofuran from methanofuran and CO2. These results establish a role for this heterodisulfide (CoM-S-S-HTP) in the reduction of CO2 to formylmethanofuran. Evidence indicates that CoM-S-S-HTP is the labile intermediate that accounts for the coupling of the reduction of 2-(methylthio)ethanesulfonic acid by the methylreductase to formylmethanofuran biosynthesis, the "RPG effect." The heterodisulfide was found to be labile in cell extracts due to enzyme-catalyzed reduction and possibly thioldisulfide exchange.
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism*; D003067:Coenzymes / Q000378:metabolism*; D019605:Euryarchaeota / Q000254:growth & development / Q000378:metabolism*; D007700:Kinetics; D008623:Mercaptoethanol / Q000031:analogs & derivatives*; D015080:Mesna / Q000378:metabolism*; D008697:Methane / Q000378:metabolism*; D010769:Phosphothreonine / Q000031:analogs & derivatives* / Q000378:metabolism; D013912:Threonine / Q000031:analogs & derivatives*
chemical_list: D003067:Coenzymes; C049349:7-mercaptoheptanoylthreonine phosphate; D010769:Phosphothreonine; D002245:Carbon Dioxide; D013912:Threonine; D008623:Mercaptoethanol; D015080:Mesna; D008697:Methane