LOCATION, CATALYTIC ACTIVITY, AND SUBUNIT COMPOSITION OF NAD-REDUCINGHYDROGENASES OF SOME ALCALIGENES STRAINS AND RHODOCOCCUS-OPACUS MR22

Six new strains of Alcaligenes enriched for and isolated as nickel-res istant bacteria resemble Alcaligenes eutrophus H16 and contain both an NAD-reducing, tetrameric soluble hydrogenase and a membrane-bound hyd rogenase. None of the soluble hydrogenases share with the Rhodococcus opacus MR11 enzyme tetramer the property of being cleaved easily into two dimeric moieties [a hydrogenase (beta delta) and an NADH:acceptor oxidoreductase (alpha gamma)], in the absence of nickel or at low ioni c strength. The soluble hydrogenase of the newly isolated strain MR22 of R. opacus equalled that of strain MR11. The absence of a membrane-b ound hydrogenase in Alcaligenes denitrificans strain 4a-2 and in Alcal igenes ruhlandii was confirmed.