Human glandular kallikrein, hK2, shows arginine-restricted specificity and forms complexes with plasma protease inhibitors.
BACKGROUND: Human glandular kallikrein (hK2) is a new potential marker for prostate cancer. It is a serine protease expressed in human prostate epithelial cells which has 78% sequence identity with prostate-specific antigen (PSA). PSA is a widely used biochemical marker for prostate cancer. METHODS: Recombinant hK2 expressed in mammalian cells ... was purified to homogeneity by immunoaffinity chromatography, using an anti-hK2 mAb. hK2 enzymatic specificity was determined on peptide substrates by N-terminal amino acid sequencing. hK2 complexes were analyzed by SDS-PAGE and Western blots. RESULTS: hK2 was found to cleave peptide substrates exclusively at selected arginine residues. An amidolytic activity of 4,100 pmol/min per microgram hK2 was obtained on the chromogenic substrate H-D-Pro-Phe-Arg-p-nitroanilide, while no activity was found on methoxysuccinyl-Arg-Pro-Tyr-p-nitroanilide, a chymotrypsin substrate used to measure PSA activity. hK2 complexed completely with alpha 1-antichymotrypsin and alpha 2-antiplasmin after 4 hr at 37 degrees C, but showed no detectable complex with antithrombin III and alpha 1-protease inhibitor under these conditions. hK2 also formed a rapid complex with alpha 2-macroglobulin. CONCLUSIONS: These results demonstrate that hK2 is an active protease with arginine-selective specificity, which forms covalent complexes with plasma protease inhibitors.
Mesh Terms:
Amino Acid Sequence, Animals, Antithrombin III, Arginine, Cell Line, Chromogenic Compounds, Cricetinae, Humans, Kallikreins, Male, Molecular Sequence Data, Oligopeptides, Peptides, Prostatic Neoplasms, Recombinant Fusion Proteins, Serine Proteinase Inhibitors, Serpins, Substrate Specificity, Tissue Kallikreins, Tumor Markers, Biological, alpha 1-Antichymotrypsin, alpha 1-Antitrypsin, alpha-2-Antiplasmin
Amino Acid Sequence, Animals, Antithrombin III, Arginine, Cell Line, Chromogenic Compounds, Cricetinae, Humans, Kallikreins, Male, Molecular Sequence Data, Oligopeptides, Peptides, Prostatic Neoplasms, Recombinant Fusion Proteins, Serine Proteinase Inhibitors, Serpins, Substrate Specificity, Tissue Kallikreins, Tumor Markers, Biological, alpha 1-Antichymotrypsin, alpha 1-Antitrypsin, alpha-2-Antiplasmin
Prostate
Date: Jan. 01, 1998
PubMed ID: 9428387
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