Divalent cation activation of deoxycholate-solubilized and -inactivated membrane reduced nicotinamide adenine dinucleotide oxidase of Bacillus megaterium KM

Abstract

After treating Bacillus megaterium KM membranes with 0.2% sodium deoxycholate, most of the membrane reduced nicotinamide adenine dinucleotide (NADH) oxidase was inactivated, and all of the membrane NADH-2,6 dichlorophenol indophenol oxidoreductase was solubilized. Dilution of the deoxycholate-treated membranes in the presence of divalent cations restored almost all of the original membrane NADH oxidase. The effectiveness of the divalent cation activation decreased in the order Ba(2+) > Ca(2+) > Mg(2+) > Mn(2+). After centrifugation, the deoxycholate-treated membranes at 100,000 x g for 1 hr, all of the NADH oxidase that was activated by a divalent cation was soluble. Cation-activated oxidase, however, was insoluble. The results show that 0.2% deoxycholate at least partially solubilizes the total electron chain from NADH to O(2) in an inactive from which can be reactivated by divalent cations with the formation of active, insoluble NADH oxidase.