Abstract: Two antioxidant peptides obtained in our previous work, Gln-Trp-Phe-Met (QWFM, 652.78) and Lys-Trp-Phe-Met (KWFM, 610.78), were used to explore the effect of pulsed electric field (PEF) on their fluorescence intensity. The results showed that the fluorescence intensity of both antioxidant peptides, which differed by N-terminal amino acid residues, especially QWFM, was changed after PEF treatment. The most significant change in fluorescence intensity of QWFM was observed at electric pulse frequency of 1 800 Hz and field intensity of 15 kV/cm. The fluorescence intensity of antioxidant peptides decreased as time elapsed after PEF treatment. The circular dichroism (CD) and nuclear magnetic resonance (NMR) spectra showed changed hydrogen bonds maintaining the β-sheet in QWFM and thus reduced β-sheet content. These results suggested that the chemical structure of antioxidant peptides and consequently their properties could be changed by PEF, which will provide a theoretical foundation for further exploitation and utilization of antioxidant peptides.

Key words: pulsed electric field (PEF), antioxidant peptide, fluorescence intensity, chemical structure