The cleavage site specificity of human prostate specific antigen for insulin-like growth factor binding protein-3

The cleavage site of human insulin-like growth factor binding protein-3 by urinary prostate specific antigen was examined. human insulin-like growth f actor binding protein-3 was incubated with urinary prostate specific antige n at 37 degrees C and its proteolyzed fragments mere separated by a reverse d phase HPLC followed by N-terminal amino acid sequence analysis, demonstra ting that the cleavage mainly occurred at Tyr-159, The synthetic peptide in cluding Tyr-159 was also cleaved at the same site, although its reaction ra te was relatively low. These results indicate that human insulin-like growt h factor binding protein-3 is specifically cleaved at Tyr-159 by prostate s pecific antigen, human insulin-like growth factor binding protein-3 was pre viously reported to be cleaved at five sites including Arg-97, Arg-132, Tyr -159, Phe-173 and Arg-179 by another group, however, prostate specific anti gen preparation is possibly contaminated by trypsin-like protease, In contr ast, our purified urinary prostate specific antigen had only a chymotrypsin -like activity, demonstrating that prostate specific antigen has the high s ubstrate specificity for human insulin-like growth factor binding protein-3 , (C) 1999 Federation of European Biochemical Societies.