Glutamine and methionine targeted pulsed electric field treatment for enhanced immune activity in pine nut Gln‐Trp‐Phe‐Met peptides

Summary The immunocompetence of an immune regulatory active Gln‐Trp‐Phe‐Met (QWFM) tetrapeptide obtained from pine nut protein was enhanced using a pulsed electric field (PEF). The effects of PEF were estimated based on phagocytosis and nitric oxide (NO) assays of RAW 264.7 macrophage cells. PEF significantly ( P < 0.05) increased the ability of the macrophages to perform neutral red phagocytosis and produce NO. The relationship between the activity and structure of the peptide was further investigated using infrared, Raman, circular dichroism (CD) and one‐dimensional nuclear magnetic resonance spectroscopies. The infrared and Raman spectra indicated that the primary structure and functional groups of the peptide were not altered by PEF treatment, while the CD revealed that the secondary structures of the peptide were affected. Furthermore, PEF treatment changed the chemical environment of the active hydrogen protons. The PEF treatment targeted the glutamine (Q) and methionine (M) in the QWFM tetrapeptide, both of which were specifically related to the immunological activity of the peptide. This overall enhancement of QWFM immunoregulatory activity was attributed to the changes in the spatial force and the state in the peptide solution system.