Catalytic properties of the heterodisulfide reductase involved in the final step of methanogenesis

FEBS Letters

Thauer, R.K.¹  Hedderich, R.¹  Berkessel, A.² 

[1] Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität Marburg, Karl-von-Frisch-Straße, D-3550 Marburg FRG;Institut für Organische Chemie, J. W. Goethe-Universität, D-6000 Frankfurt am Main 50, FRG

关键词: Methanogenic bacteria;    Methanogenesis;    Coenzyme M;    Mercaptoheptanoylthreonine phosphate;    7-;    Disulfide reductase;    (Methanobacterium thermoautotrophicum;    Methanosarcina barkeri);    H-S-CoM or coenzyme M;    2-mercaptoethanesulfonate;    H-S-HTP;    7-mercaptoheptanoyl (L) threonine phosphate;    CH3-S-CoM or methyl-coenzyme M;    2-(methylthio)ethanesulfonate;    CoM-S-S-HTP;    heterodisulfide of H-S-CoM and H-S-HTP;   

DOI  :  10.1016/0014-5793(89)81062-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Reduction of the heterodisulfide of coenzyme M (H-S-CoM) and 7-mercaptoheptanoyl(L)threonine phosphate (H-S-HTP) is a partial reaction in methanogenesis. The CoM-S-S-HTP reductase mediating this reaction has thus far not been studied. We report here that the enzyme from Methanobacterium thermoautotrophicum and Methanosarcina barkeri catalyzes the reduction of CoM-S-S-HTP with reduced viologen dyes and, in the reverse direction, the oxidation of H-S-CoM plus H-S-HTP to the heterodisulfide by methylene blue. The CoM-S-S-HTP reductase from M. thermoautotrophicum (strain Marburg) was partially purified (30-fold) to a specific activity of 10 μmol·min⁻¹·mg protein⁻¹. The enzyme was highly substrate specific: e.g. neither the heterodisulfide derived from 6-mercaptohexanoylthreonine phosphate nor the homodisulfide of H-SCoM or of HSHTP was reduced. The D-enantiomer of CoM-S-S-HTP was, however, converted at 35% of the specific rate of the L-form. Apparent K_m and apparent V_max values for substrates and products were determined.

【 授权许可】

Unknown