Open AccessPurification and properties of an F 420 H 2 dehydrogenase from Methanosarcina mazei Gö1
Author(s) -
Abken HansJörg,
Deppenmeier Uwe
Publication year - 1997
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1997.tb12649.x
Subject(s) - methanosarcina , methanosarcina barkeri , chemistry , hydrogenase , oxidoreductase , biochemistry , molecular mass , enzyme , formate dehydrogenase , cofactor , methanogenesis , archaea , organic chemistry , methane , gene
Abstract The F 420 H 2 dehydrogenase is part of the energy‐conserving F 420 H 2 :heterodisulfide oxidoreductase system in Methanosarcina mazei Gö1. The enzyme was purified 75‐fold to apparent homogeneity from washed membranes. The molecular mass as determined by both native gel electrophoresis and gel filtration was 115 000. The purified enzyme was composed of five different polypeptides with molecular masses of 40, 37, 22, 20, and 16 kDa and contained 7 mol S 2− and 7 mol Fe. The specific activity was 17 U mg protein −1 (apparent V max ) using F 420 H 2 as electron donor ( K m = 7 μM) and methylviologen and metronidazole as electron acceptors at pH 8.5 at a temperature of 39°C. The enzyme also catalyzed the reduction of 2,3‐dimethyl‐1,4‐naphthoquinone, 2‐methyl‐1,4‐naphthoquinone and tetramethyl‐ p ‐benzoquinone. The protein did not exhibit hydrogenase activity since F 420 was not reduced by hydrogen and H 2 production from F 420 H 2 was not observed. In contrast to the F 420 H 2 dehydrogenase from Archaeoglobus fulgidus , the enzyme from Methanosarcina mazei Gö1 was similar to the corresponding protein of Methanolobus tindarius with respect to molecular mass and subunit composition. However, the proteins of the methanogenic organisms are different in cofactor content, since evidence is presented that the enzyme from Methanosarcina mazei Gö1 contains FAD.