title: Identification of a phosphopeptide in bovine alpha s1-casein digest as a factor influencing proliferation and immunoglobulin production in lymphocyte cultures.
abstract: Digestion of bovine alpha s1-casein with bovine trypsin produced peptide(s) with an inhibitory effect on concanavalin A-induced proliferation of mouse spleen cells. One of these peptides was isolated from the alpha s1-casein digest following ultrafiltration, hydroxyapatite chromatography and reversed-phase HPLC, and amino acid composition and sequence analyses showed it to be sequence 59-79 from the phosphoserine-rich region of alpha s1-casein. The isolated peptide significantly inhibited the concanavalin A-induced proliferation of mouse spleen cells and rabbit Peyer's patch cells, whereas it enhanced the lipopolysaccharide- and phytohaemagglutinin-induced proliferation of both cells. The peptide displayed mitogenic activity in the cell cultures without the commercial mitogen, and significantly enhanced immunoglobulin production. Moreover, residues 1-25 from the phosphoserine-rich region of bovine beta-casein had a similar effect on the proliferation of mouse spleen cells and rabbit Peyer's patch cells stimulated or not stimulated by the commercial mitogen. These results indicate that caseinophosphopeptides may act as a humoral immunostimulator in cell cultures.
authors.affiliation: Laboratory of Food Bioscience, Faculty of Agriculture, Shinshu University, Nagano-ken, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Hata
authors.forename: S
authors.initials: S
authors.lastname: Higashiyama
authors.forename: H
authors.initials: H
authors.lastname: Otani
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002364:Caseins / Q000737:chemistry* / Q000378:metabolism; D002417:Cattle; D002455:Cell Division / Q000187:drug effects*; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D005260:Female; D007136:Immunoglobulins / Q000096:biosynthesis*; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D010748:Phosphopeptides / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D011817:Rabbits; D013154:Spleen / Q000166:cytology; D014357:Trypsin / Q000378:metabolism
chemical_list: D000596:Amino Acids; D002364:Caseins; D007136:Immunoglobulins; D010446:Peptide Fragments; D010748:Phosphopeptides; D003208:Concanavalin A; D014357:Trypsin