RT Journal Article SR Electronic(1) A1 Mura, G. M. A1 Pedroni, P. A1 Pratesi, C. A1 Galli, G. A1 Serbolisca, L. A1 Grandi, G.YR 1996 T1 The [Ni-Fe] hydrogenase from the thermophilic bacterium Acetomicrobium flavidum JF Microbiology, VO 142 IS 4 SP 829 OP 836 DO https://doi.org/10.1099/00221287-142-4-829 PB Microbiology Society, SN 1465-2080, AB Biochemical analysis of the soluble hydrogenase from the thermophilic organism Acetomicrobium flavidum revealed that the enzyme is an a2ß2 tetramer, with the a and ß subunits having a molecular mass of 50 kDa and 25 kDa, respectively. The most important biochemical properties of the enzyme are a specific activity of 77 μmol min-1 (mg protein)-1 a K m for methylviologen of 0.2 mM, a pH optimum of 7.5 and a T 50 of about 70 †C. In addition, the enzyme is remarkably stable to oxygen inactivation, retaining full activity after 24 h exposure to air. By using oligodeoxynucleotides designed on the basis of the N-terminal sequences of the two subunits, the corresponding genes have been isolated and sequenced. When compared to the other hydrogenases so far characterized, the A. flavidum hydrogenase appears to be a typical [Ni-Fe] enzyme. The hydrogenase was expressed in Escherichia coli at high levels in a soluble form but it was not active. The analysis of the recombinant large subunit showed that it was not post-translationally processed at its C-terminus., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-142-4-829