Activation and inactivation of methanol: 2-mercaptoethanesulfonic acid methyltransferase from Methanosarcina barkeri.
Methanol is converted to methane by crude extracts of Methanosarcina barkeri. The first reaction involved in this process, is catalyzed by methanol:2-mercaptoethanesulfonic acid methyltransferase (EC 2.1.1.-). The methyltransferase has an optimum at pH 6.5 and is not inhibited by 2-bromoethanesulfonic acid. Pyridoxal-5'-phosphate acts as an inhibitor (Ki = 0.30 mM). The methyltransferase was tested in the presence of 2-bromoethanesulfonic acid, which inhibits the conversion of 2-(methylthio)ethanesulfonic acid to methane. The reaction is subject to activation and inactivation. Inactivation is brought about by the presence of oxygen, flavin mononucleotide, flavin adenine dinucleotide, and 2-(methylthio)ethanesulfonic acid, the product of the reaction. Activation of the system requires the presence of ATP and Mg2+ and of hydrogen. Hydrogen can be replaced by enzymatic systems, such as pyruvate dehydrogenase, which deliver free hydrogen.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000476:Alkanesulfonates / Q000494:pharmacology; D017738:Alkanesulfonic Acids; D004789:Enzyme Activation; D019605:Euryarchaeota / Q000201:enzymology*; D006859:Hydrogen / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000494:pharmacology; D000432:Methanol / Q000378:metabolism; D008780:Methyltransferases / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology; D011732:Pyridoxal Phosphate / Q000494:pharmacology
D000476:Alkanesulfonates; D017738:Alkanesulfonic Acids; C018853:2-bromoethanesulfonic acid; D011732:Pyridoxal Phosphate; D006859:Hydrogen; D000255:Adenosine Triphosphate; D008780:Methyltransferases; C036890:methanol-2-mercaptoethanesulfonic acid methyltransferase; D008274:Magnesium; D010100:Oxygen; D000432:Methanol