SURFACTANTS- AND OXIDANTS-RESISTANT ALKALINE PROTEASES FROM COMMON CARP (CYPRINUS CARPIO L) PROCESSING WASTE

Abstract

Intestine from Cyprinus carpio L., an important fish in the Brazilian Aquaculture, is proposed in this work as a source of alkaline protease. The intestine crude extract was submitted to a partial purification by ethanol precipitation. The fraction 30–70% (v/v) of ethanol concentration showed higher recovery and specific activity when compared with the crude extract and was submitted to further studies. The optimal temperature and pH were found to be 50C and 11.0, respectively. The enzymatic activity was activated by nonionic surfactants and retained more than 60% of their initial proteolytic activity in the presence of the ionic surfactants. Almost 50% of enzymatic activity was retained in the presence of 5% (v/v) of hydrogen peroxide. The high proteolytic activity at 50C and alkaline pH, together with its stability in the presence of the surfactants and oxidants tested, indicate that this alkaline protease can well be used in detergent formulations. PRACTICAL APPLICATIONS Hydrolytic enzymes have been employed in a range of applications including processes in the food, textile and pharmaceutics industries. Among theses enzymes, proteases correspond for the highest sales on the enzyme market. In the present time, most proteolytic enzymes are extracted from bacteria (genus Bacillus). These biomolecules can also be extracted from the viscera of several fish species. This study relates the partial purification and physical chemical characteristics of alkaline protease found in the Cyprinus carpio intestine, one of the most important species for the world aquaculture. Surfactants and oxidant agents were also used to assay the stability of this enzyme. Therefore, this communication contributes to the optimization of the use of fish by-products as well as the discovery of enzymes displaying desirable properties.