The effect of pH and temperature on the stability and enzymatic activity of prostatic acid phosphatase. Studies on the optimization of a continuous monitored determination of acid phosphatase, II.

The catalytic activity and the stability of prostatic acid phosphatase were studied with respect to pH and temperature: 1. Enzymatic activity in serum decreases with time, and the rate of decrease depends on pH and temperature. Half life times were estimated. 2. To preserve at least 90% of its original activity, serum must be cooled as soon as possible below room temperature and/or the pH must be lowered to 6. 3. Considering the effect of pH on side reactions and kinetic parameters, a pH of 5.2 is recommended for the assay. 4. Between 25 and 37 degrees C, the value for Km app, in the absence of alcohols, is constant within the limits of error. In the presence of alcohols there is a significant increase of Km app at lower temperatures, and higher substrate concentrations are needed to avoid nonsaturation of the enzyme. vmax increases with temperature. Inactivation is observed above 45 degrees C, especially in the presenc of alcohols. 5. The Arrhenius plot shows a strict linear regression between 20 degrees C and 40 degrees C, in the presence or absence of 1,4-butanediol, 1,5-pentanediol or 1,6-hexanediol. 6. Temperature conversion factors for catalytic activity were calculated to be: 1.33 (25 to 30 degrees C), 1.96 (25 to 37 degrees C) and 1.47 (30 to 37 degrees C).