Identification of Antimicrobial Peptides of Native and Heated Hydrolysates from Hen Egg White Lysozyme.

Hen eggs are a source of bioactive compounds, of which the hen egg white lysozyme (HEWL) protein. HEWL has a demonstrated antibacterial activity. The aim of this study was to evaluate the antimicrobial activity of native and heated HEWL hydrolysates obtained through hydrolysis with pepsin and to identify their peptides using the reversed phase high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (RP-HPLC-ESI-MS-MS) analysis. Native and heat-treated HEWL was hydrolyzed with pepsin at pH 1.2, and their antibacterial activity was tested against Escherichia coli and Staphylococcus carnosus. Two of the hydrolysates obtained presented high antibacterial activity against Gram-positive and Gram-negative bacteria. Native HEWL hydrolysate was a bactericide at 2.0 mg/mL against E. coli. Fifty-one peptide sequences were identified on the two hydrolysates. Peptides identified are cationic peptides. These peptides are rich in Lys and Arg cationic amino acids and have Trp in their sequences.