The electron transfer from hydrogenase and formate dehydrogenase to polysulfide reductase in the membrane of Wolinella succinogenes

Abstract

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 and formate or H 2 as donor decreased hyperbolically with the amount of liposomes fused to the membrane fraction, while the activities of formate dehydrogenase, of hydrogenase and of polysulfide reductase were not affected. The electron transport activity with H 2 did not decrease upon fusion to the membrane fraction of liposomes containing the isolated hydrogenase. Electron transport with fumarate as acceptor was nearly unaffected by the dilution of the membrane fraction with liposomes containing vitamin K-1. The results confirm that menaquinone is not involved in the electron transport from H 2 or formate to polysulfide, and argue against the existence of a stable electron transport complex within the membrane which is made up of a dehydrogenase and a polysulfide reductase molecule. Instead, the electron transport complex appears to be formed reversibly by diffusion and collision of the enzyme molecules.