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Torres-Larios, A; Fuentes-Silva, D; Mendoza-Hernandez, G; Stojanoff, V; Palomares, LA; Zenteno, E; Rodriguez-Romero, A (2007)

CRYSTALLIZATION AND IDENTIFICATION OF THE GLYCOSYLATED MOIETIES OF TWO ISOFORMS OF THE MAIN ALLERGEN HEV B 2 AND PRELIMINARY X-RAY ANALYSIS OF TWO POL

ACTA CRYSTALLOGR F 63():787-791
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Latex from Hevea brasiliensis contains several allergenic proteins that are involved in type I allergy. One of them is Hev b 2, which is a beta-1,3-glucanase enzyme that exists in different isoforms with variable glycosylation content. Two glucanase isoforms were isolated from trees of the GV-42 clone by gel filtration, affinity and ion-exchange chromatography. Isoform I had a carbohydrate content of about 20%, with N-linked N-acetyl-glucosamine, N-acetyl-galactosamine, fucose and galactose residues as the main sugars, while isoform II showed 6% carbohydrate content constisting of N-acetyl-glucosamine, fucose, mannose and xylose. Both isoforms were crystallized by the hanging-drop vapour-diffusion method. Isoform I crystals were grown using 0.2 M trisodium citrate dihydrate, 0.1 M Na HEPES pH 7.5 and 20%( v/ v) 2-propanol, but these crystals were not appropriate for data collection. Isoform II crystals were obtained under two conditions and X-ray diffraction data were collected from both. In the first condition ( 0.2 M trisodium citrate, 0.1 M sodium cacodylate pH 6.5, 30% 2-propanol), crystals belonging to the tetragonal space group P4(1) with unit-cell parameters a = b = 150.17, c = 77.41 angstrom were obtained. In the second condition [ 0.2 M ammonium acetate, 0.1 M trisodium citrate dihydrate pH 5.6, 30%( w/ v) polyethylene glycol 4000] the isoform II crystals belonged to the monoclinic space group P2(1), with unit-cell parameters a = 85.08, b = 89.67, c = 101.80 angstrom, beta = 113.6 degrees. Preliminary analysis suggests that there are four molecules of isoform II in both asymmetric units.