Title: Evidence for the non-glycoprotein nature of high molecular weight glutenin subunits of wheat
Authors: Roels, SP ×
Delcour, Jan #
Issue Date: Nov-1996
Series Title: Journal of Cereal Science vol:24 issue:3 pages:227-239
Abstract: An isolation and purification procedure for wheat high molecular weight glutenin subunits (HMW-GS) involving no steps expected to cause deglycosylation of glycoproteins was developed to allow removal of the maximum amount of carbohydrates not covalently linked to HMW-GS. Flour was defatted and then extracted with 50% n-propanol (50% n-PrOH) to remove arabinogalactans and glucose-containing material. HMW-GS were extracted with 50% n-PrOH containing 5% beta-mercaptoethanol, precipitated in 60% n-PrOH, alkylated and recovered by precipitation. The partially purified HMW-GS were separated by cation exchange chromatography and resulting fractions purified by RP-HPLC. The purified HMW-GS contained only 0.1% of glucose (corresponding to 51-59 monosaccharide residues per 100 HMW-GS molecules) and no other amino or neutral sugars. The HMW-GS gave a positive reaction in a periodate-digoxigenin glycan detection assay when labelled in solution (with or without periodate oxidation) but not when labelled directly on-the-blot. HMW-GS expressed in Escherichia coli a micro-organism without glycosylation capabilities, reacted in an identical way. Possible reasons are given for the difference in results obtained after labelling in solution or on-the-blot. No positive reaction between the purified HMW-GS and mannose-specific Galanthus nivalis agglutinin was observed. The presence of N-acetylglucosamine in HMW-GS has been previously reported(20). Since neither mannose nor N-acetylgalactosamine were found in the HMW-GS, and these proteins lack the sequon necessary for N-glycosylation, only O-linked GlcNAc moieties are possible. This modification could not be detected using a galactosyltransferase labelling assay. Taken together these results suggest that HMW-GS are not glycosylated. (C) 1996 Academic Press Limited
ISSN: 0733-5210
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Centre for Food and Microbial Technology
× corresponding author
# (joint) last author

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