Chemical Constituents and Hydrogenase Binding in Cell Envelopes of Vibrio succinogenes

Abstract

The particulate hydrogenase of Vibrio succinogenes is solubilized during treatment of cell envelopes at pH 11.0. Alkali-solubilized enzyme requires sulfhydryl compounds for activity. At neutral pH, soluble enzyme is reincorporated into alkalitreated cell envelopes and no longer requires an additional activator. In the present study, cell envelopes prepared by lysing cells with ethylenediaminetetraacetic acid plus lysozyme (EDTA-lysozyme) were used to determine the chemical composition of cell envelopes and derived pH 11.0 soluble and insoluble fractions and to investigate some properties of the binding and activation of alkali-solubilized hydrogenase. Lysis with EDTA-lysozyme resulted in the formation of spheroplast ghosts. The derived cell envelopes contained 61% protein, 3% ash, 23% lipid, and 1% phosphorus. The alkali-treated cell envelopes contained 50% protein, 2% ash, 24% lipid, and 1% phosphorus. The ash from cell envelopes and alkali-treated cell envelopes was rich in iron and phosphorus and also contained calcium, copper, magnesium, sodium, and zinc. Virtually all of the weight of the ashed samples was accounted for by the oxides of these metals. Since the reconstitution of particulate hydrogenase was achieved with pH 11.0 supernatant solution and precipitate, intact mucopeptide is not essential for hydrogenase binding. Release of hydrogenase during EDTA-lysozyme lysis was found to depend upon an apparent structural change which occurs in the membranes during extended storage at -20 C.