title: An epitope residing in carbohydrate chains of a sea squirt antigen termed Gi-rep.
abstract: O-Glycosidically linked oligosaccharides (Gp-1 beta-b) were liberated from a large size glycopeptide (GP) fraction (Gp-1) in a Pronase digest of a sea squirt antigen termed Gi-rep by the treatment with 0.1 N NaOH per 1 mol/L of NaBH4. Gp-1 beta-b as well as Gp-1 and the intact antigen was capable of inducing a remarkable erythema in the skin of patients with asthma with sea squirt allergy at its concentration of 10 micrograms/ml. N-Glycoside GP fractions (Gp-1 beta-a and Gp-2 beta) having the allergenic activity were also prepared as alkali-resistant GPs from Gp-1 and the other relatively small size GP fraction (Gp-2) of the Pronase digest, respectively, after the alkali treatment. Chemically, the three allergenically active preparations were rich in galactosamine, glucosamine, and fucose in common, although the N-linked carbohydrates were much larger in size than O-linked carbohydrates. Accordingly, it has been expected that the epitope of the sea squirt antigen corresponds to certain oligosaccharide units residing in both of the O- and N-linked carbohydrate chains of the antigen. This suggestion was consistent with the observation that the allergenic activity of Gi-rep was significantly unstable to the periodate oxidation but substantially stable not only to acid, alkali, and heat treatments but also to the enzymatic proteolysis with Pronase E.
mesh_terms: D000818:Animals; D000941:Antigens / Q000032:analysis*; D002241:Carbohydrates / Q000032:analysis* / Q000276:immunology; D000939:Epitopes; D006023:Glycoproteins; D010084:Oxidation-Reduction; D010504:Periodic Acid / Q000378:metabolism; D014561:Urochordata / Q000276:immunology*
chemical_list: D000941:Antigens; D002241:Carbohydrates; D000939:Epitopes; C053192:Gi-rep antigen, Sea squirt; D006023:Glycoproteins; D010504:Periodic Acid; C009288:metaperiodate