Bioactive properties of peptides derived from enzymatic hydrolysis of cod muscle myosin with trypsin, chymotrypsin and elastase

Low molecular weight peptides derived by controlled enzymatic hydrolysis from fish by-products and underutilized fish species have been shown to have potential application in the food, pharmaceutical and nutraceutical industries. A recently developed process to extract pure fish proteins from fish by-products (called fish protein isolates), which are usually rich in pro-oxidants and oxidative susceptible lipids, has made it possible to prepare fish protein hydrolysates without serious oxidative and color problems during processing and in the final product. Several studies have been conducted already to determine bioactive properties of fish protein hydrolysates with certain proteolytic enzyme mixtures and whole fish muscle extracts from different fish species. However, very limited studies have been done on fish protein isolate hydrolysates in terms of their functionality and bioactivity.;For this research project, myosin, which is the most abundant single muscle protein in fish muscle (and fish protein isolates), was extracted from Atlantic cod (Gadus morhua) and then hydrolyzed by three separated individual enzymes (trypsin, chymotrypsin and elastase), which were also extracted from Atlantic cod (Gadus morhua). Low molecular weight peptides were separated from the myosin hydrolysates by ultrafiltration using 5 and 30 kDa membranes. The fractionated peptides were then tested for various bioactive properties, such as antioxidant capacities and angiotensinconverting enzyme (ACE) inhibition. All peptide fractions were finally analyzed by liquid chromatography coupled with tandem mass spectrometry.;The results show that peptides with antioxidative and ACE inhibitory properties can be produced by enzymatic hydrolysis. Low molecular weight peptides show higher antioxidative and ACE inhibitory activities. The bioactive properties are dependent on the type of enzyme used, as well as the degree of hydrolysis and molecular size. Chymotrypsin derived peptides showed higher antioxidant potential than trypsin and elastase derived one, while trypsin derived peptides had the lowest IC50 values for ACE-Inhibition. Higher degrees of hydrolysis (%DH) seem to increase bioactive properties until about 30%, while hydrolysates with 43 %DH showed decreased antioxidant activity and increased ACE-inhibitory activities. Mass Spectrometry results discovered over 5000 low molecular weight peptides (less than 10 amino acids residues long) through De novo sequencing.