Identity of Prostate Specific Antigen and the Semen Protein P30 Purified by a Rapid Chromatography Technique

Abstract

Previous investigators have reported the identity of prostate specific antigen (PSA) and the semen protein p30, but data to support these claims have not been published. We report here the rapid and continuous purification of PSA using a simple two column chromatography technique originally developed for purification of p30. Using commercial antisera to PSA and original antisera to p30 for detection, we show that the two glycoproteins have identical purification profiles by this technique which uses cation exchange chromatography and sizing chromatography. The antigens also have identical molecular weights by gel electrophoresis and gel filtration. Furthermore, both antigens correspond to the same prominent protein band in seminal plasma by sodium dodecylsulfate polyacrylamide gel electrophoresis. On commercial immunoassay for PSA, purified p30 gives a calibration curve identical to the commercial PSA kit calibrator (Pros-checkTM PSA Radioimmunoassay, Yang Laboratories). We conclude that PSA and the semen protein p30 are identical and can be easily purified by a rapid continuous technique.

Analysis of Monoclonal Antibodies to Prostate-Specific Antigen: Reactivity with Native and Recombinant Prostate-Specific Antigen

“…The nonreduced native PSA showed two bands with molecular weights of 32 and 28 kD. Although reports of only a single band for PSA have been described [9], more recent findings are in agreement with our observation of multiple fragments [6,11]. Epitope analysis revealed that 42% of the Workshop antibodies reacted with the N-terminus of PSA suggesting this region may possess highly immunogenic determinants.…”

“…This would indicate that, at least in the baculovirus expression system, the proenzyme sequence is involved in the secretion process. Moreover, since the inactive proenzyme is not found in human seminal fluid [4,6,8,9], this would appear to support a role for the proenzyme sequence in the extracellular secretion of PSA.…”

“…PSA assays from different manufacturers have produced quite variable results [9,10]. These discrepancies may be due to different antibody reactivity or specificity for free PSA and PSA-ACT, assay format or calibration [10,11].…”

Two step procedure for purification of enzymatically active prostate-specific antigen from seminal plasma

“…Beside PSA isoforms, no other proteins were detected in gel stained with silver nitrate. Table 2 Amino-terminal sequence of f-PSA(seminal plasma) 25 Ile-Val-Gly-Gly-Trp-Glu-Cys-Glu-Lys-His-full length 26 Val-Gly-Gly-Trp-Glu-Cys-X-Lys-His-Ser-N − 1 N-terminus. This represent 30% of f-PSA.…”

Expression, Purification, and Characterization of Deglycosylated Human Pro-Prostate-Specific Antigen

“…PSA is 78% homologous to hK2, another member of the kallikrein family of serine proteases that is also produced in the prostate epithelium (17); however, unlike PSA, hK2 has a trypsin-like substrate specificity (18). Both PSA and hK2 have been purified from seminal fluid (19,20) and antigenic epitopes for each have been identified and exploited to develop radioimmunoassays for differential diagnosis of prostate cancer and benign prostatic hyperplasia (21)(22)(23). Although hK2 can be separated from PSA by affinity chromatography on immobilized benzamidine or aprotinin (24), many commercially available preparations of PSA contain trace amounts of hK2 which has led to some confusion regarding the specific enzymatic activities attributable to PSA (24 -26).…”