Study On The Myofibril-Bound Seriner Protease Of Modori And Its Inhibition In Big-Head Fish Surimi Production

The objective of this paper is to study the mechanism of modori in surimi production and to find some native food grade inhibitor. We choose the bighead fish as our study object because it is a kind of freshwater fish.69mg Myofibril-bound serine protease (MBSP) from bighead fish skeletal muscle (4.0kg) was purified with purification (59468-fold) and recovery (62％). The purification method combines a acid treatment (under the conditions of 2mol/L KCl, pH4.0) to the myofibril fraction, then purified by column chromatographic steps on Arginine-Sepharose 4B. All steps are carried out at 0-4℃. The optimum temperature and pH of the enzyme were 50℃and 7.0, when Boc-Phe-Ser-Arg-MCA was used as substrate. The MBSP activity was stable when pH was between 6.0-8.0 (50℃) and temperature was at 30℃(pH8.0).Soybean trypsin inhibitor (STI) and Phaseolus Calcaratus Roxb trypsin inhibitor (PCRTI) were mixed with the MBSP and myobibrils respectively, and their inhibitory effect on MBSP and on myofibrillar protein degradation was investigated.Throuth the SDS-PAGE, in the presence of STI and PCRTI, the proteolysis of myosin heavy chain (MHC) was greatly suppressed even after incubation for 1h at 55℃.