AN EPITOPE RESIDING IN CARBOHYDRATE CHAINS OF A SEA SQUIRT ANTIGEN TERMED GI-REP

[摘要] O-Glycosidically linked oligosaccharide (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 .mu.g/ml. N-Glycoside GP fractions (Gp-1.beta.-.alpha. 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 the O- and N-lnked 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 treatment but also to the enzymatic proteolysis with Pronase E.

[发布日期] 1987-07-01