Is the subunit of prostatic phosphatase active? Reversible denaturation of prostatic acid phosphatase.

Prostatic acid phosphatase [E.C. 3.1.3.2.] is a dimeric protein consisting of two identical subunits. This enzyme was denatured in 6 M urea solution at pH 2.5, and kinetical analysis of reactivation by dilution was performed. At low protein concentrations a second-order kinetics for reactivation of phosphatase, with rate constant 8.3 m M-1sec-1, was observed. At higher protein concentrations the reactivation obeyed first-order kinetics. These results seem to exclude the possibility that subunits of the prostatic phosphatase are catalytically active and suggest that the association of two monomers is necessary for full activity.