Reconstitution of highly purified proton-translocating pyrophosphatase from Rhodospirillum rubrum

Abstract

Membrane-bound PPase is of interest as it functions in various organisms as a coupling factor between electron transport and PPi synthesis and is involved in the energy transduction pathway as an independent alternative to the ATPase system [1-4]. PPi hydrolysis in chromatophores of Rhodospirillum rubrum caused a change in the fluorescence of added 8-anilino-naphtalene-l-sulfonic acid [5], an uptake of phenyl dicarbaundecaborane anion [6] and a pH change of the outer medium [7]. Therefore, it was concluded that chromatophore PPase translocates protons across the membrane coupled to PPi hydrolysis, apparently in a manner corresponding to that of the chromatophore ATPase. Further investigation of membrane-bound PPase has been impeded by the lack of an efficient method of isolation. Although a method of purifying the PPase has been reported [8], only recently has a method of obtaining a highly purified mem-