Methyl-coenzyme-M reductase from Methanobacterium thermoautotrophicum (strain Marburg). Purity, activity and novel inhibitors.
Methyl-coenzyme-M reductase from Methanobacterium thermoautotrophicum (strain Marburg) was purified to a stage where, besides the alpha, beta and gamma subunits, no additional polypeptides were detectable in the preparation. Under appropriate conditions the enzyme was found to catalyze the reduction of methyl-CoM with 7-mercaptoheptanoylthreonine phosphate (H-S-HTP) to CH4 at a specific rate of 2.5 mumol.min-1.mg protein-1. This finding contradicts a recent report that methyl-CoM reductase is only active when some contaminating proteins are present. The two polypeptides encoded by the open reading frames ORF1 and ORF2 of the methyl-CoM reductase transcription unit did not co-purify with the alpha, beta and gamma subunits. They were neither required nor did they stimulate the activity under the assay conditions. 3-Bromopropanesulfonate (apparent Ki = 0.05 microM) and 2-azidoethanesulfonate (apparent Ki = 1 microM) were found to be two new competitive inhibitors of methyl-CoM reductase. Both inhibitors were considerably more effective than the "classical" 2-bromoethanesulfonate (apparent Ki = 4 microM).
Ellermann
J
J
Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität Marburg, Federal Republic of Germany.
Rospert
S
S
Thauer
R K
RK
Bokranz
M
M
Klein
A
A
Voges
M
M
Berkessel
A
A
D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D019605:Euryarchaeota / Q000201:enzymology* / Q000235:genetics; D005796:Genes; D005798:Genes, Bacterial; D007700:Kinetics; D015080:Mesna / Q000031:analogs & derivatives / Q000378:metabolism; D009097:Multienzyme Complexes / Q000302:isolation & purification* / Q000378:metabolism; D010088:Oxidoreductases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D013379:Substrate Specificity; D001616:beta-Galactosidase / Q000235:genetics
D009097:Multienzyme Complexes; D010088:Oxidoreductases; C023895:methyl coenzyme M methylreductase; D001616:beta-Galactosidase; D015080:Mesna