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

Abstract 1. 1. The specific activity of the membrane-bound ATPase of Streptococcus cremoris HA was 1.30 μmol p i /mg protein/min. 2. 2. K m for ATP as substrate was 0.8 mM. 3. 3. The pH optimum was 8.0 at +37°C. 4. 4. The ATPase was maximally activated with Mg 2+ /ATP molar ratio of 1:2. 5. 5. Cations activated the enzyme in order: Mg 2+ > Co 2+ > Mn 2+ > Zn 2+ > Ca 2+ > K 2+ > Na + . 6. 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.