Human glandular kallikrein, hK2, shows arginine-restricted specificity and forms complexes with plasma protease inhibitors

Autor: Stephen D. Mikolajczyk, Mohammad S. Saedi, Abhay Kumar, Lisa S. Millar
Rok vydání: 1998
Předmět:
Zdroj: The Prostate. 34:44-50
ISSN: 1097-0045
0270-4137
DOI: 10.1002/(sici)1097-0045(19980101)34:1<44::aid-pros6>3.0.co;2-k
Popis: 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 μg 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 α1-antichymotrypsin and α2-antiplasmin after 4 hr at 37°C, but showed no detectable complex with antithrombin III and α1-protease inhibitor under these conditions. hK2 also formed a rapid complex with α2-macroglobulin. CONCLUSIONS These results demonstrate that hK2 is an active protease with arginine-selective specificity, which forms covalent complexes with plasma protease inhibitors. Prostate 34:44–50, 1998. © 1998 Wiley-Liss, Inc.
Databáze: OpenAIRE
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