[Functional characteristics of the membrane preparations from the cells of the thermophilic hydrogen bacterium. Pseudomonas thermophila].

The electron transport chain (ETC) of Pseudomonas thermophila K-2 was examined by the amperometric determination of O2 uptake by the preparations of membranes isolated by ultracentrifugation at 14,000 g. Amytal and cyanide were found to inhibit endogenous respiration of membranes from freshly grown cells. The membrane preparations, after exhaustion of endogenous substrates in them, oxidized NADH and succinate at rates of 4.00 and 0.83 mumole/min per 1 mg of membrane protein, respectively. The oxidation of NADH was inhibited by rotenone and cyanide, while the oxidation of succinate, only by cyanide. Maxima corresponding to NADH and iron-containing proteins were found in the fluorescence spectra of membrane preparations from Ps. thermophila K-2. Endogenous NADH was not susceptible either to incubation of the preparations in the air, or to hydrogen being bubbled through. These results and the data reported in literature make it possible to conclude that the membrane preparations from Ps. thermophila K-2 contain all the ETC components similar to the mitochondrial ones.