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Seminal plasma contains "BPSA," a molecular form of prostate-specific antigen that is associated with benign
S D Mikolajczyk1, L S Millar, K M Marker
1Hybritech Incorporated, a subsidiary of Beckman Coulter, Inc., San Diego, California 92196-9006, USA. sdmikolajczyk@beckman.com
Background:
We previously reported that levels of BPSA, a modified form of prostate-specific antigen (PSA), are significantly elevated in prostate transition-zone tissue exhibiting nodular hyperplastic changes associated with the presence of benign prostatic hyperplasia (BPH). BPSA was purified and found to contain a characteristic clip between Lys182 and Ser183. We now describe the identification of BPSA in seminal plasma.
Methods:
PSA was purified from seminal plasma by immunoaffinity chromatography. The purified PSA was further resolved by hydrophobic interaction chromatography, and the individual PSA forms were analyzed by gel electrophoresis and N-terminal amino-acid sequencing.
Results:
BPSA comprised about 8% of the PSA in pooled seminal plasma, and was identical to BPSA purified from prostate tissues. BPSA was cleanly resolved from all active and inactive forms of PSA. Other inactive forms of PSA in seminal plasma consisted largely of PSA clipped at Lys145, though about 30% of the inactive seminal plasma PSA was intact, mature PSA.
Conclusions:
BPSA represents a distinct form of inactive PSA in the seminal plasma that may represent a specific marker for the biochemical changes associated with nodular development in the prostate transition zone found in patients with BPH.