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Membrane‐bound F 420 H 2 ‐dependent heterodisulfide reductase in methanogenic bacterium strain Göl and Methanolobus tindarius
Author(s) -
Deppenmeier U.,
Blaut M.,
Mahlmann A.,
Gottschalk G.
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)80670-e
Subject(s) - hydrogenase , oxidoreductase , electron acceptor , reductase , chemistry , membrane , electron transfer , electron transport chain , cofactor , stereochemistry , enzyme , biochemistry , organic chemistry
Washed membrane or cytoplasmic fractions of the methanogenic bacterium strain Göl catalyzed the oxidation of coenzyme F 420 H 2 with a variety of electron acceptors. The F 420 H 2 ‐oxidizing activity of the cytoplasmic fraction could be assigned to a NADP + :F 420 oxidoreductase. The membrane fraction but not the cytoplasmic fraction catalyzed the oxidation of F 420 H 2 with the concomitant reduction of the heterodisulfide of 2‐mercapto‐ethanesulfonate and 7‐mercaptoheptanoylthreonine phosphate (CoM‐S‐S‐HTP) at a rate of 100protein according to the following equation: F 420 H 2 +CoM‐S‐S‐HTP → F 420 + CoM + HTP‐SH. The activity depended linearly on the membrane protein up to a concentration of 60The physiological electron acceptor CoM‐S‐S‐HTP could not be replaced by the corresponding homodisulfides CoM‐S‐S‐CoM and HTP‐S‐S‐HTP or by NADP + . A membrane‐bound F 420 H 2 ‐dependent CoM‐S‐S‐HTP reductase was also detected in Methanolobus tindarius exhibiting a specific activity of 75protein. The absence of a F 420 ‐dependent hydrogenase in this organism excludes the involvement of this enzyme in electron transfer from H 420 H 2 to CoM‐S‐S‐HTP.