Subcellular distributions and properties of rat testicular acid phosphatases

Synopsis Acid phosphatase activities againstp-nitrophenyl phosphate, -naphthyl phosphate -naphthyl phosphate, naphthol AS-BI phosphate, -glycerophosphate and -glycerophosphate were studied in whole homogenates and subcellular fractions of rat testes. The mitochondrial-lysosomal fraction (the 9000 g sediment) was the most active against all these substrates, but a high specific activity was also present in the soluble fraction (105,000 g supernatant). The effect of various inhibitors and activators onp-nitrophenyl phosphate hydrolysis was different in these fractions. The soluble enzyme was markedly stimulated by Co²⁺, Mg²⁺, Mn²⁺, Ni²⁺ and Zn²⁺. The particulate enzyme was inhibited by sodium fluoride, sodium tartrate and sodium molybdate, whereas the soluble activity was sensitive to Cd²⁺, Cu²⁺ and Sn²⁺ as well as to formaldehyde and glutaraldehyde. The soluble acid phosphatase is mainly localized within the seminiferous tubules. The high sensitivity of the soluble activity to the commonly used fixatives may interfere in the histochemical demonstration of the enzyme.