Characterization of separated prostatic acid phosphatase forms in normal and castrated rats

We have investigated the effects of castration and androgen replacement on the kinetic characteristics of rat prostatic acid phosphatases (AP). Chromatography on DEAE-cellulose DE-23 and on Sephacryl S-200 allowed the separation of lysosomal (S-1) and secretory (S-3) forms of AP. In addition, these techniques revealed a third enzymic form (S-2), which eluted in the void volume of the Sephacryl S-200 column and which occurred in significant amounts only 15 days after castration. The S-2 form was extremely resistant (K₁ 1500 μM) to L-tartrate inhibition in the 15-day post-castration rat which is in contrast to the behaviour of S-2 (K_i 145 μM) in control animals. The appearance of this unidentified AP form can explain the dramatic drop in the per cent inhibition of total rat AP observed between 7 and 15 days post-castration.