Factors Affecting Deoxycholate Inactivation and Mg++ Reactivation of Bacillus megaterium KM Membrane Nicotinamide Adenine Dinucleotide (Reduced Form) Oxidase

摘要

Decay of the reduced nicotinamide adenine dinucleotide oxidase of Bacillus megaterium KM membranes was prevented by storage in 10% (v/v) glycerol or 0.4% bovine serum albumin. Differential rates of solubilization of components of the oxidase system by 0.4% deoxycholate was demonstrable at 4 C. The amount of Mg⁺⁺ necessary for maximal oxidase reactivation increased with increasing amounts of deoxycholate-inactivated oxidase. Mg⁺⁺ activation of deoxycholate-inactivated oxidase was partially temperature-dependent. Maximal activation was observed at 37 C, but only partial activation took place at 4 C. A small amount of deoxycholate was required for Mg⁺⁺ activation of deoxycholate-inactivated oxidase. Two pH optima were found for Mg⁺⁺ activation of deoxycholate-inactivated oxidase, pH 5.3 and 7.3. Significant amounts of activation of the inactive oxidase occurred in the absence of Mg⁺⁺ with an optimum at pH 5.0, with essentially no Mg⁺⁺-independent activation demonstrable at pH 7.0.