THE ELECTRON-TRANSFER FROM HYDROGENASE AND FORMATE DEHYDROGENASE TO POLYSULFIDE REDUCTASE IN THE MEMBRANE OF WOLINELLA-SUCCINOGENES

Freeze-thawing of the membrane fraction of Wolinella succinogenes with sonic liposomes containing vitamin K-1 gave an apparently homogeneous particle preparation. The specific electron transport activity based on membrane protein of these particles with polysulfide as acceptor an d formate or H-2 as donor decreased hyperbolically with the amount of liposomes fused to the membrane fraction, while the activities of form ate dehydrogenase, of hydrogenase and of polysulfide reductase were no t affected. The electron transport activity with H-2 did not decrease upon fusion to the membrane fraction of liposomes containing the isola ted hydrogenase. Electron transport with fumarate as acceptor was near ly unaffected by the dilution of the membrane fraction with liposomes containing vitamin K-1. The results confirm that menaquinone is not in volved in the electron transport from H-2 or formate to polysulfide, a nd argue against the existence of a stable electron transport complex within the membrane which is made up of a dehydrogenase and a polysulf ide reductase molecule. Instead, the electron transport complex appear s to be formed reversibly by diffusion and collision of the enzyme mol ecules.