Electron transport-linked compared with proton-induced ATP generation in Thiobacillus novellus

The apparently soluble electron-transport system, that does not sediment when centrifuged at 144,000 x g or 300,000 x g for 3 hr, catalyzes oxidative phosphorylation with an efficiency comparable to that of an intact mitochondrial system. While the proton-induced phosphorylation occurs in whole cells, crude cell-free extracts, and supernatants from low-speed centrifugation, it does not occur in either the 144,000 or 300,000 x g supernatant fractions. The data show that oxidative energy can be conserved as ATP under conditions that are incompatible with the basic postulate of the chemiosmotic hypothesis.