Improved Determination of Prostatic Acid Phosphatase

We have modified a previously described method for de-termining acid phosphatase, with thymolphthalein mono-phosphate as substrate, to increase its sensitivity. We assessed effects of serum on variables influencing acid phosphatase activity as measured by this method. The method is shown to be not completely specific for prostatic acid phosphatase. The importance of standardizing methodology in measurement of enzyme activities is demonstrated. A method for measuring acid phosphatase [ortho-phosphoric-monoester phosphohydrolase (acid opti-mum), EC 3.1.3.2] activity in serum, with thymol-phthalein monophosphate as substrate, was described by Roy et al. (1) and is the basis of a “kit ” metho