CONTAMINATION OF PURIFIED PROSTATE-SPECIFIC ANTIGEN PREPARATIONS BY KALLIKREIN HK2

This paper ascertained the contamination by hK2 of two types of PSA pr eparation, that of Sensabaugh and Blake (J. Urol., 144: 1523, 1990) an d that of Deperthes et al (J. Androl., 17: 659, 1996). In the first pr ocedure, the free forms of hK2 co-migrated with PSA during the CM-Seph adex and the Sephacryl S-200 steps. By contrast, in the second procedu re a very high proportion of hK2 was separated from PSA. In two differ ent Sensabaugh and Blake procedures, the hK2 contamination per mu g. o f PSA was found to be respectively 0.3 and 1.0 ng. We conclude that hK 2 is a quantitatively minor contaminant of some PSA preparations. That contamination is probably of little consequence for PSA standardizati on but it could lead to erroneous conclusions in enzymatic studies of PSA.