Studies on aryl phosphate hydrolysis by human acid phsophatases

Acid phosphatases from human tissues were investigated with respect to the cleavage of six different aryl phosphates. The enzymes, except the prostatic one, showed increasing Km values with increasing substrate concentrations at a constant pH. Electrophilic substitution of the aromatic ring lowered the reaction velocity, but apparently did not change the Km. The optimum hydrolysis was at pH 3.0--6.0 without any regular pattern, which could depend on the substrate configuration.