Chemistry of allergens. XXII. Isolation and characterization of three new antigens from the dialysates of six successive pepsin hydrolyses of beta-lactoglobulin.
Twelve new antigens previously have been demonstrated in the pepsin digests of milk proteins. The term "new antigen" is defined as an antigen with a specificity distinct from that of the protein from which it was generated. Three new antigens (alpha-, beta-, and D2i) polypeptides and one nonantigenic gamma-polypeptide have been isolated from the dialysates of six successive pepsin hydrolyses of beta-lactoglobulin. The alpha- and beta-polypeptides were 1/5 and D2i was 1/10-1/20 as potent immunogens as precursor beta-lactoglobulin as determined by the Schultz-Dale technique. The minimum observed amounts of new antigen eliciting maximum response of uterine strips in the Schultz-Dale tests were: alpa-D2, 50 ng; beta-D2, 15 ng; beta-D3; 10 ng; and D2i, 1,000 ng. Except for the alpha-polypeptide, the amino acid contents of the polypeptides differed markedly from that of beta-lactoglobulin. The beta-polypeptide has been tentatively identified as a 33 amino acid fragment of beta-lactoglobulin (3,910 daltons). The gamma-polypeptide has been tentatively identified as a 12 amino acid fragment of beta-lactoglobulin (1,372 daltons).
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D000941:Antigens / Q000302:isolation & purification*; D001322:Autoanalysis; D002850:Chromatography, Gel; D004589:Electrophoresis, Disc; D000939:Epitopes; D005260:Female; D006168:Guinea Pigs; D007114:Immunization; D007117:Immunization, Secondary; D007782:Lactoglobulins / Q000276:immunology*; D008970:Molecular Weight; D009584:Nitrogen / Q000032:analysis; D010434:Pepsin A; D010455:Peptides / Q000302:isolation & purification; D014364:Tryptophan / Q000032:analysis; D014599:Uterus / Q000276:immunology
D000596:Amino Acids; D000941:Antigens; D000939:Epitopes; D007782:Lactoglobulins; D010455:Peptides; D014364:Tryptophan; D010434:Pepsin A; D009584:Nitrogen