Component C of the methylreductase system of Methanobacterium.
1981; Elsevier BV; Volume: 256; Issue: 9 Linguagem: Inglês
10.1016/s0021-9258(19)69427-5
ISSN1083-351X
AutoresWilliam L. Ellefson, R. S. Wolfe,
Tópico(s)Microbial bioremediation and biosurfactants
ResumoComponent C of the methyl coenzyme M methylreductase system of Methanobacterium thermoautotrophicum has been purified to homogeneity with a 17% recovery of initial units.The native protein has a molecular weight of 300,000 and is composed of three different subunits with masses of 68,000, 45,000, and 38,500.They are present in equal proportion, suggesting a stoichiometry of a2, &, yz in the native protein.The amino acid composition reveals a preponderance of acidic amino acid residues.The protein is yellow, having an absorption maximum at 425 n m and a shoulder at 455 nm.Reconstitution of the methyl coenzyme M methylreductase activity was linearly dependent on added component C. Component C has been detected in cell extracts of other methanogens.The terminal step of methane formation requires the participation of three components: component A, an oxygensensitive, M, = 500,000 protein complex having hydrogenase activity; component B, an oxygen-sensitive, colorless cofactor; and component C, an oxygen-stable acidic protein (1).Component C has been identified recently as the 2-(methy1thio)ethanesulfonic acid methylreductase (2).In the presence of Mg'+, ATP, and hydrogen, these components reduce CH&-CoM1 to methane and HS-CoM.Here we report the purification and physical properties of component C; a preliminary report in abstract form has appeared (3).EXPERIMENTAL PROCEDURES' Materials .Trlzrna bare, Ter.Coomassie R250.dansyl chloride, dansyldted dmlno acld Standardr.dexcransulfate, and a l l p m t e i n Standards w e ~e purchased from 81911.Cheng-Chln polyamide
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