Crossed immunoelectrophoretic analysis of proteins from Antarctic krill (Euphausia superba) with special reference to serine proteinases

Immunochemical characterization of proteins from Antarctic krill (E. superba) and particularly serine proteinases was performed by crossed immunoelectrophoresis (CIE). A reference pattern with 34 arbitrarly numbered immunoprecipitates was established for a crude krill extract using IgG rabbit antiserum. A zymographic technique for detection of proteolytic activity was applied and revealed 4 casein-positive antigens. Introduction of different affinity media as intermediate gels in CIE demonstrated several proteins which strongly interacted with Sepharose-bound arginine and Con A. These results suggest the presence of trypsin-like enzymes and other serine proteases and a high content of glycoproteins with alfa-D-mannopyranoside and alfa-D-glycopyranoside residues. The CIE method thus offers a reliable and reproducible tool for identification and characterization of different krill enzymes as well as application in process control, when purifying individual proteins/enzymes. Moreover this technology may serve as a fingerprinting method suitable for biological studies such as classification of geographical subpopulations, genotyping a specific species as well as comparisons between different species.