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N 5 , N 10 ‐Methylenetetrahydromethanopterin dehydrogenase from Methanobacterium thermoautotrophicum has hydrogenase activity
Author(s) -
Zirngibl C.,
Hedderich R.,
Thauer R.K.
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)80649-4
Subject(s) - hydrogenase , methanobacterium , chemistry , electron acceptor , carbon monoxide dehydrogenase , dehydrogenase , nad+ kinase , enzyme , stereochemistry , dehydrogenation , cofactor , medicinal chemistry , nuclear chemistry , catalysis , biochemistry , carbon monoxide , archaea , gene
N 5 , N 10 ‐Methylenetetrahydromethanopterin dehydrogenase from Methanobacterium thermoautotrophicum (strain Marburg) was purified under anaerobic conditions to apparent homogeneity and a specific activity of approximately 750 μol/min/mg protein. Polyacrylamide gel electrophoresis under native and denaturing conditions revealed that the enzyme is composed of only one polypeptide with an apparent molecular mass of 43 kDa. The purified enzyme catalyzed the dehydrogenation of N 5 , N 10 ‐methylenetetrahydromethanopterin (CH 2 =H 4 MPT) (apparent K m ≡20 μM) to N 5 , N 10 ‐methenyltetrahydromethanopterin (CH≡H 4 MPT) in the absence of any added electron acceptors. One mol of H 2 was generated per mol CH≡H 4 MPT formed, indicating that protons served as electron acceptor. Coenzyme F 420 , NAD, NADP and viologen dyes were not reduced by CH 2 =H 4 MPT. The dehydrogenase also catalyzed the reverse reaction, the reduction of CH≡H 4 MPT to CH 2 =H 4 MPT with H 2 . The data indicate that CH 2 =H 4 MPT dehydrogenase from M. thermoautotrophicum is a novel type of hydrogenase.