Abstract: In this study, crude extract concentrate from silver carp eggs was prepared and purified by Q Sepharose Fast Flow anionic chromatography and subsequent Sephacryl S-200 molecular sieve chromatography to obtain partially purified casepase inhibitor (CPI) named as CPI-I. Azocasein assay was used to determine the inhibitory activity of crude extract concentrate and CPI-I. In addition, the heat stability of CPI-I activity was evaluated using the fluorescent peptide Z-Phe-Arg-MCA as substrate. The purification factor of CPI-I relative to silver carp egg homogenate was 72, and the recovery rate was 10.25%. Based on the molecular weight standard curve obtained from Sephacryl S-200 molecular sieve chromatography and the results of reverse zymographic analysis, the molecular weight of CPI-I was preliminarily identified as 89 kD. The results of periodic acid-Schiff (PAS) staining demonstrated that CPI-I was a glycoprotein. CPI-I could inhibit cathepsin L from silver carp meat and showed remarkable heat stability.

Key words: silver carp egg, cysteine protease inhibitors, purification, characterization