Purification and characterization of antioxidative peptides from Salmon protamine hydrolysate

Protamine, derived from fish milt, which is normally discarded as an industrial by-product in the process of fish plant, was hydrolyzed with pancreatin. Salmon protamine hydrolysate was found to possess antioxidative activity against hydroxyl, 2,2-diphenyl-1-picrylhydrazyl and superoxide anion radicals. Through consecutive chromatographic methods including size exclusion, ion exchange chromatography and reverse-phase high performance liquid chromatography (HPLC), a series of peptide fractions with high antioxidative activities were obtained. Peptide with highest antioxidative activity was identified to be Pro-Arg matching 1-2 and 16-17 residues of the salmon protamine by electrospray ionization mass spectrometry and database search. These results provided sufficient and scientific information for the marketing of health food supplemented with protamine hydrolysate and added further support for the wide applications of fish milt.