title: High molecular weight glucan of the culinary medicinal mushroom Agaricus bisporus is an alpha-glucan that forms complexes with low molecular weight galactan.
abstract: An alpha-glucan was isolated from the culinary medicinal mushroom A. bisporus by hot water extraction, ethanol precipitation and DEAE-cellulose chromatography. The resulting material showed a single HMW peak excluded from a Sephadex G50 column that could completely be degraded by alpha-amylase treatment. After heating in 1% SDS a small additional peak of low MW eluted from the G50 column. The monosaccharide composition of the main peak was evaluated by HPLC, and was found to consist of a majority of glucose (97.6%), and a minor proportion of galactose (2.4%). Methylation analysis and degradation by alpha-amylase indicated the presence of an alpha-glucan with a main chain consisting of (1(R)4)-linked units, substituted at O-6 by alpha-D-glucopyranose single-units in the relation 1:8. Mono- (13C-, 1H-NMR) and bidimensional [1H (obs.),13C-HSQC] spectroscopy analysis confirmed the alpha-configuration of the Glcp residues by low frequency resonances of C-1 at delta 100.6, 100.2, and 98.8 ppm and H-1 high field ones at delta 5.06, 5.11, and 4.74 ppm. The DEPT-13C-NMR allowed assigning the non-substituted and O-substituted -CH(2) signals at delta 60.3/60.8 and 66.2 ppm, respectively. Other assignments were attributed to C-2, C-3, C-4, C-5 and C-6 of the non-reducing ends at delta 71.8; 72.8; 70.0; 71.3 and 60.3/60.8 ppm, respectively. The minor proportion of galactose that was demonstrated was probably derived from a complex between the alpha-glucan and a low molecular weight galactan.
authors.affiliation: Plant Research International, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB Wageningen, Netherlands.
authors.forename: Fhernanda R
authors.initials: FR
authors.lastname: Smiderle
authors.forename: Guilherme L
authors.initials: GL
authors.lastname: Sassaki
authors.forename: Jeroen
authors.initials: J
authors.lastname: van Arkel
authors.forename: Marcello
authors.initials: M
authors.lastname: Iacomini
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Wichers
authors.forename: Leo J L D
authors.initials: LJ
authors.lastname: Van Griensven
mesh_terms: D000364:Agaricus / Q000378:metabolism*; D002236:Carbohydrate Conformation; D002848:Chromatography, DEAE-Cellulose; D002851:Chromatography, High Pressure Liquid; D005685:Galactans / Q000737:chemistry / Q000378:metabolism*; D005936:Glucans / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D008970:Molecular Weight; D010946:Plants, Medicinal / Q000737:chemistry*; D000516:alpha-Amylases / Q000378:metabolism
chemical_list: D005685:Galactans; D005936:Glucans; C040088:1,4-glucan; D000516:alpha-Amylases