Structural and immunological properties of arabinogalactan polysaccharides from pollen of timothy grass (Phleum pratense L.).
Extracts from pollen of timothy grass (Phleum pratense L.) contain up to 20% arabinogalactan proteins (AGPs). Separation of the AGP polysaccharide moieties by tryptic digestion, size exclusion chromatography (GPC), and reverse phase HPLC yielded arabinogalactan fractions AG-1 and AG-2 with molecular weights of approximately 15,000 and approximately 60,000Da, respectively. The backbones of both polysaccharides are composed of (1-->6)-linked beta-D-galactopyranosides with beta-D-GlcUAp or 4-O-Me-beta-D-GlcUAp at their terminal ends as revealed by chemical analysis, FT-IR, MALDI-MS, and NMR spectroscopy. AG-1 contains a small number of beta-l-Araf side chains while AG-2 possesses a variety of (1-->3)-linked units, which consist of beta-l-Araf-(1-->, alpha-l-Araf-(1-->3)-beta-l-Araf-(1-->, and alpha-l-Araf-(1-->5)-beta-l-Araf-(1--> as well as a small number of longer arabinogalactan side chains. In contrast to crude pollen extracts, the immunological properties of the arabinogalactan mixture reveal an IgG4 reactivity instead of IgE reactivity. Structural properties of timothy pollen arabinogalactan might thus influence the immune response.
Brecker
Lothar
L
Research Center Borstel, Division of Immunochemistry, Parkallee 22, D-23845 Borstel, Germany. lothar.brecker@univie.ac.at
Wicklein
Daniel
D
Moll
Hermann
H
Fuchs
Elmar C
EC
Becker
Wolf-Meinhard
WM
Petersen
Arnd
A
D000485:Allergens / Q000276:immunology*; D002240:Carbohydrate Sequence; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D005685:Galactans / Q000737:chemistry* / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology; D013058:Mass Spectrometry; D015394:Molecular Structure; D008970:Molecular Weight; D019906:Nuclear Magnetic Resonance, Biomolecular; D031784:Phleum / Q000276:immunology*; D011058:Pollen / Q000276:immunology*; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000276:immunology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D017550:Spectroscopy, Fourier Transform Infrared
D000485:Allergens; D005685:Galactans; D007074:Immunoglobulin G; D011135:Polysaccharides, Bacterial; C005653:arabinogalactan