Isolation and partial characterization of two antigenic glycoproteins from rye-grass (Lolium perenne) pollen

Abstract

Two glycoproteins were purified from a buffer extract of rye-grass (L. perenne) pollen. Both migrated as single bands on sodium dodecyl sulfate/polyacrylamide gels. Glycoprotein 1 (0.8 mg/g of pollen) had an apparent MW of 33,000 and contained 95% protein and 5% carbohydrate. The monosaccharides glucose, galactose, mannose, arabinose and N-acetylglucosamine were present in the proportions 3:3:1:2:1. Glycoprotein 2 (0.4 mg/g of pollen) had an apparent MW of 68,000 and contained 88% protein and 12% carbohydrate. The monosaccharides glucose, galactose, mannose, fucose, xylose, arabinose and N-acetylglucosamine were present in the proportions 4:7:13:5:8:6:6. This glycoprotein bound concanavalin A and Lotus tetragonolobus (asparagus pea) lectin. Radioallergosorbent (RAST) inhibition tests with serum from a rye-grass sensitive human subject showed that Glycoprotein 1 is an effective allergen, whereas Glycoprotein 2 has less allergenic activity. A method for performing both lectin-binding assays and RAST inhibition tests using microtiter trays is described.