Acid phosphatases of dog testis and a Leydig cell tumor

Acid phosphatase activities were measured with five different substrates after fractionation with Sepharose 6B and DE-52 cellulose chromatography of homogenate from normal adult dog testis and a testicular tumor. The tumor showed a positive 3 beta-hydroxysteroid dehydrogenase reaction and was diagnosed as a Leydig cell adenoma. The fractionations gave three separate enzyme activities in the normal testis and two enzymes in the tumor. All were sensitive to sodium fluoride, but differed from each other in pH-optima and the response to Co2+ and Zn2+. Enzymes I and II were identical in both tissues. The latter with a smaller molecular weight was activated by Zn2+ but not by Co2+ and had slightly higher pH-optimum (4.5) than enzyme I (optimum at pH 3.5). The third enzyme was activated by Co2+ and Zn2+ and had the highest pH-optimum (pH 5.5). It was called enzyme IV due to its resemblance to a similar activity in other mammalian species.