Physicochemical and immunochemical characterization of allergenic proteins from rye-grass (Lolium perenne) pollen prepared by a rapid and efficient purification method

Abstract

Three fractions of rye-grass (Lolium perenne) pollen extract have been isolated by preparative isoelectric focusing (i.e.f.) and characterized in terms of physicochemical and immunochemical properties. The purified components were designated 'R7' and 'R14' on the basis of their positions in relation to other rye-grass pollen extract components on SDS/polyacrylamide-gel electrophoresis and their apparent molecular masses were assessed as 31 and 11 kDa respectively. On i.e.f., R14 split into two components, one acidic (pl 5.0) and one basic (pl 9.0), termed 'Rl4a' and 'Rl4b' respectively, and R7 focused at pl 5.8. R7 and R14a were shown to be allergenic by skin-prick test and all three components were recognized by rye-grass-pollen-specific human IgE. On SDS/polyacrylamide-gel electrophoresis and i.e.f., R7 behaved in a manner identical with that shown by an authentic sample of Rye I and gave an amino acid analysis similar to published data Immunochemistry 3, 91-100] for Rye group-I isoallergens; the amino acid sequence of the first 27 N-terminal amino acids was also determined. Physicochemical analysis revealed that R14a was equivalent to Rye II and 14b to Rye III. Preparative i.e.f. followed by gel-permeation chromatography proved to be a rapid and efficient method for purifying the allergenic components of Rye I (R7), Rye II (Rl4a) and Rye III (Rl4b) from rye-grass pollen extract.

Purification and Characterization of Four β-Expansins (Zea m 1 Isoforms) from Maize Pollen

“…A ␤-expansin (CIM1) from soybean (Glycine max) cell cultures has been characterized partially (Downes et al, 2001) but not with respect to its potential wall extension properties. It is apparent from sequence analysis that ␣-expansins typically lack motifs for N-linked glycosylation, whereas ␤-expansins characteristically possess such motifs and have been shown to be glycosylated in the few examples studied (Marsh, 1975;Howlett and Clarke, 1981;Cottam et al, 1986;Petersen et al, 1995;Knox and Suphioglu, 1996b;Downes et al, 2001). However, we doubt that ␤-expansins from vegetative tissues cause early cell wall breakage or have a pH optimum Ͼ5, as found for Zea m 1, because acidinduced extension of native walls (not heat inactivated) from grass coleoptiles does not exhibit these properties, and it is likely that ␤-expansins are major catalysts of acid-induced extension in grass walls Li et al, 1993;Cho and Kende, 1997;Cosgrove et al, 1997).…”

Carbohydrate Binding Modules: Biochemical Properties and Novel Applications

“…This distinct CBM family, known today as the expansin family, was first identified as the grass allergen of group I, the major allergen from grasses (63). Some genes from this family have been characterized (3,41,56), but their function in plant pollen became clear only years later when the identity between these proteins and a second group of expansins, known as ␣-expansins, was established (39). Expansins are cell wall proteins that are involved in the loosening of the plant cell wall during plant growth as well as in the fruit softening process (40).…”

Isolation of cDNA encoding a newly identified major allergenic protein of rye-grass pollen: intracellular targeting to the amyloplast.

“…Elevated levels of IgE specific for this allergen have been detected in sera of up to 95% of grass pollenallergic individuals (8). Antigenically cross-reacting proteins corresponding to Lol pI, known as the group I allergens, are present in the pollen of other clinically important grasses (9)(10)(11)(12).…”