Acid phosphatase in the rat prostate: comparison with other organs.

Properties of acid phosphatase in the rat ventral prostate were compared with those in seven other organs in adult male rats by the electrophoretic mobility in acrylamide gels, susceptibility to reactions with inhibitors, and by their response to castration and subsequent testosterone replacement. The enzyme in the spleen exhibited the highest values of Km and Vmax. These values in the prostate, the liver, and the kidney showed an intermediate level, while the lowest level was found in the heart, the lung, the adrenals, and the seminal vesicle. Upon electrophoresis, a total of six isoenzyme bands were resolved. Two major zones of activity were noted. They were the slow-moving anodal bands (isoenzymes 1,2, and 3) and the fast-moving cathodal bands (isoenzymes 4,5, and 6). The spleen possessed the highest number of isoenzymes (bands 1,2,4,5 and 6) and the prostate had three (bands 1,2, and 3). The heart contained only one (band 2). Two isoenzymes (bands 1 and 2) were found in remaining organs. Results of the effects of inhibitors showed that NaF inhibited all six isoenzymes, while L(+)tartrate inhibited mainly those in the anodal zone. D(-)tartrate and formaldehyde showed no significant inhibition to any of the isoenzymes. PCMB (para-chloromercuribenzoic acid) was found to be a specific inhibitor for isoenzyme 3. Upon castration in the hosts, the enzyme activity in the prostate, the liver, and the seminal vesicle was significantly reduced. This reduction in enzyme activity involved all isoenzymes in these three organs, but isoenzyme 3 in the prostate disappeared completely after castration. The activities of these isoenzymes were restored by testosterone replacement. These results indicate that acid phosphatase in rat tissues has multiple forms; each has its own electrophoretic mobility in acrylamide gels, sensitivity to inhibitors, and response to hormonal manipulation. Isoenzyme 3 is specific to the prostate and is uniquely sensitive to PCMB inhibition and to androgen stimulation.