Glycoprotein Allergens in Pollen of Timothy IV.

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Abstract
Heat treatment of the glycoprotein allergen with alkaline tritiated borohydride released carbohydrate material in the molecular weight (MW) range 500–2,000 daltons. The radioactivity of the highest MW carbohydrate fraction was low, indicating the presence of alkali-stable hydroxyproline-arabinose linkages. N-acetylglucosaminitol containing 3H was detected in the hydrolysate of the low-MW carbohydrate, indicating that some of the carbohydrate is bound to the protein chain through a N-glycosidic linkage between N-acetylglucosamine and asparagine. The presence of this linkage was also suggested by fast atom bombardment mass spectrometry of pronase-digested allergen. The glycoprotein seems to contain only a few carbohydrate chains made up of a total of 25 monosaccharide units. Methylation analysis indicated that the carbohydrate moiety consists of (1) galactopyranosyl units as branching points linked through 1,3,6-positions or as terminal galactopyranosyl residues, (2) mannopyranosyl groups as part of the chain either as 1,3- or 1,4-linked units, and (3) arabinofuranosyl groups as branching points linked through 1,3,5-positions or as part of the chain, either as 1,3- or 1,5-linked units or as terminal arabinofuranosyl residues.