Properties of the N,N'-dicyclohexylcarbodiimide resistant ATPase of Streptococcus cremoris

1. The specific activity of the membrane-bound ATPase of Streptococcus cremoris HA was 1.30 mumol Pi/mg protein/min. 2. Km for ATP as substrate was 0.8 mM. 3. The pH optimum was 8.0 at +37 degrees C. 4. The ATPase was maximally activated with Mg2+/ATP molar ratio of 1:2. 5. Cations activated the enzyme in order: Mg2+ greater than Co2+ greater than Mn2+ greater than Zn2+ greater than Ca2+ greater than K+ greater than Na+. 6. The enzyme was inhibited by oligomycin (27-77%), sodium azide (13-33%) and ouabain (15-22%). N,N'-dicyclohexylcarbodiimide had no effect on the enzyme activity.