(1) The porcine myofibrillar protein hydrolysate obtained by a papain treatment showed antioxidative activity in a system of linolenic acid peroxidation induced by Fe²⁺. The five peptides, DSGVT, IEAEGE, DAQEKLE, EELDNALN, and VPSIDDQEELM, have been characterized as antioxidative peptides.
(2) Four peptides showed antioxidative activity at a concentration of 0.1% in an aqueous lipid peroxidation system. The sample concentration for DSGVT and IEAEGE was 1.5mM, for DAQEKLE was 1.2mM, for EELDNALN was 1.1 mM, and for VPSIDDQEELM was 0.8 mM, DSGVT having no antioxidative effect at 0.1% ^[1].
(3) Their short peptides with amino acid deletions at the C- or N-termini were synthesized. The antioxidative activity gradually decreased with decreasing peptide length. Replacing the charged amino acids in these peptide sequences with Ala also affected their antioxidative activity. We hypothesize that the anions from acidic amino acids and the cations from iron interacted with each other and inactivated the prooxidant, Fe (II) ^[1].

Peptide obtained by hydrolysis of pork's myofibrillar protein by protease treatment (papain or actinase E).

[1] Egusa S A, Nishimura T. Antioxidative properties of peptides obtained from porcine myofibrillar proteins by a protease treatment in an Fe (II)-induced aqueous lipid peroxidation system.[J]. Bioscience Biotechnology & Biochemistry, 2013, 77(11):2201-4.