Characterization of a cellular immunostimulating peptide from a soybean protein fraction digested with peptidase R
2009
Egusa, S.(Shinshu Univ., Minamiminowa, Nagano (Japan)) | Otani, H.
An immunostimulating glutamine-rich peptide was purified from a soybean protein fraction digested with peptidase R produced by Rhizopus oryzae (Ro-digest) by a combination of SP-Sepharose column chromatography and reversed-phase high-performance liquid chromatography. The purified peptide was supposed to be located at or near the glutamine-rich region 202 to 222 of the glycinin G4 subunit. The peptide significantly increased the number of CD8sup(+), CD11bsup(+), and CD49bsup(+) cells in C3H/HeN mouse spleen cell cultures, while 2 chemically synthesized glutamine-rich peptides corresponding to residues 202 to 213 (QQQQQQKSHGGR) and residues 214 to 225 (KQGQHQQEEEEE) of the glycinin G4 subunit increased the number of interleukin (IL)-12sup(+)CD11bsup(+) cells. The peptide 202-213 also significantly increased the number of CD49bsup(+), IL-2sup(+)CD4sup(+), and interferon-gammasup(+)CD4sup(+) cells and stimulated the cytotoxic activity of spleen cells toward the human erythroleukemia cell line K562. These results indicate that the glutamine-rich region of the soybean glycinin G4 subunit stimulates the cellular immune system in mouse spleen cell cultures.
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