TAILIEUCHUNG - Báo cáo Y học: Amidolytic activity of prostatic acid phosphatase on human semenogelins and semenogelin-derived synthetic substrates

In addition to kallikrein hK3, a serine protease generally reported as PSA (prostate-speci®c antigen), at least two other enzymes in human seminal plasma also cleave syn-thetic peptidyl substrates derived from the sequence of human semenogelins. We have identi®ed one of these as prostatic acid phosphatase (PAP), a major component of prostatic ¯uid whose physiological function is unclear. | Eur. J. Biochem. 269 390-395 2002 FEBS 2002 Amidolytic activity of prostatic acid phosphatase on human semenogelins and semenogelin-derived synthetic substrates Michele Brillard-Bourdet1 Sophie Rehault1 Luiz Juliano2 Michele Ferrer1 Thierry Moreau1 and Francis Gauthier1 1 Laboratory of Enzymology and Protein Chemistry INSERM EMI-U 00-10 University Francois Rabelais Faculty of Medicine Tours France 2Departamento de Biofisica Escola Paulista de Medicina Universidade Federal de Sao Paulo Sào Paulo Brazil In addition to kallikrein hK3 a serine protease generally reported as PSA prostate-specific antigen at least two other enzymes in human seminal plasma also cleave synthetic peptidyl substrates derived from the sequence of human semenogelins. We have identified one of these as prostatic acid phosphatase PAP a major component of prostatic fluid whose physiological function is unclear. The other is a high Mr basic protein present at low concentrations in seminal plasma and that remains to be characterized. PAP was purified to homogeneity from freshly ejaculated seminal plasma. Its N-terminal sequence and its phosphatase properties hydrolysis of para-nitrophenylphosphate at low pH were determined and its inhibition by sodium fluoride measured. Both purified and commercial PAP also had amidolytic activity on peptide substrates derived from the semenogelin sequence at neutral and slightly basic pH. The kcat Km values were in the 102-103 M-1-s-1 range using fluorogenic semenogelin-derived substrates whose peptidyl moiety included cleavage sites that had been identified ex vivo. PAP cleavage sites differed from those of hK3 and were mainly at P1 Gln residues or between residues bearing hydroxyl groups. PAP amidolytic activity was poorly inhibited by all currently used wide spectrum proteinase inhibitors. Only 3-4 dichloroisocoumarin and benzamidine inhibited purified PAP. Purified human seme-nogelin was cleaved by purified and commercial PAP at neutral pH the two main .

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