Evaluation of protease activity in the cell extract of Gammarus from Bijgerd (Charmahal va Bakhtiari) fresh cold water.

Gammarus is an arthropod, Crustacean, from the family of Gammaridae, which is divided into freshwater and saline populations. Gammarus is widespread throughout freshwater habitats and represents as dominant both in invertebrate species in freshwater habitats and the number of biomasses. Moreover, Gammarus is among the most sensitive aquatic invertebrates to chemical stressors which can live in cold waters. In this research to measure the activity level of protease enzymes, azocasein- a chromogenic and nonspecific substrate for proteaseswas used. The enzyme hydrolyzes casein and cleaves the azo dye from casein which has a maximum absorbance at 440 nm. Here, total proteases activity was measured at temperature ranges from 4 ° C to 50 ° C and the optimum temperature of protease activity was observed at 16 ° C. Furthermore, the activity of the protease was measured at a pH ranges from 2 to 10 which based on the results an optimum pH for activity was observed at pH 7 to 7.5. Followingly, PMSF and benzoyl glycine inhibitors were used respectively to estimate the amounts of serine protease and cysteine proteases in the cell extract. The results revealed that the level of serine protease was less than 5% while that of cysteine protease was 15%. As a result, the amount of aspartic proteases in the understudy species was estimated to be 80%. According to the results it can be concluded that Gammarus contains a considerable amounts of cold-adopted aspartic protease which can be purified and exploited in dairy industries.

کلیدواژه ها:

Gammarus ، aspartic proteases ، chromogenic substrate ، casein ، optimum pH