At temperatures between 45 and 50 C, staphylococcal acid phosphatase purified 44-fold had maximal activity at pH 5.2 to 5.3. However, the enzyme was most stable in the alkaline range (pH 8.5 to 9.5) at temperatures below 50 C. Iodoacetate and ethylenediamine-tetraacetic acid were effective inhibitors, whereas mercaptoethanol and Cu2+ acted as stimulators. The energy of activation for hydrolytic cleavage of the synthetic substrate, p-nitrophenyl phosphate, was 19.5 Kcal/mole. Km for the same substrate was 4.5 × 10−4m. The purified enzyme was most active against the substrates p-nitrophenyl phosphate and glyceraldehyde 3-phosphate.
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