BIOLOGICAL-ACTIVITY OF PROSTATE-SPECIFIC ANTIGEN ISOLATED BY SODIUM DODECYL SULFATE-POLYACRYLAMIDE GEL-ELECTROPHORESIS AND ELECTROELUTION

Human prostate-specific antigen (PSA), a 33 kDa kallikrein-like serine protease, occurring in the prostate, in seminal plasma and in blood, was prepared under nonreducing conditions in an enzymatically active f orm from seminal plasma by sodium dodecyl sulfate-polyacrylamide gel e lectrophoresis (SDS-PAGE), followed by fast copper staining, electroel ution from gel slices and diaIysis against isotonic phosphate-buffered saline (PBS). Enzymatic activity was demonstrated for the first time directly by cleavage of semenogelin, one of the biological substrates of PSA, isolated by the same procedure, i.e. SDS-PAGE and electroeluti on, but from seminal vesicle fluid. The purified PSA formed SDS-stable complexes with the two major extracellular protease inhibitors in blo od, alpha(1)-antichymotrypsin (alpha(1)-ACH) and alpha(2)-macroglobuli n (alpha(2)-M). PSA isolated under reducing conditions was enzymatical ly inactive and could not bind to the protease inhibitors alpha(1)-ACH and alpha(2)-M.