Carbohydrate structural analysis of wheat flour arabinogalactan protein.
The water-extractable arabinogalactan protein (AGP) was isolated from bread wheat flour (Triticum aestivum L. variety Cadenza) and the structure of the arabinogalactan (AG) carbohydrate component was studied. Oligosaccharides, released by hydrolysis of the AG with a range of AGP-specific enzymes, were characterised by Matrix Assisted Laser Desorption Ionisation (MALDI)-Time of Flight (ToF)-Mass Spectrometry (MS), MALDI-ToF/ToF high energy collision induced dissociation (CID) and Polysaccharide Analysis by Carbohydrate gel Electrophoresis (PACE). The AG is composed of a β-(1→3)-D-galactan backbone with β-(1→6)-D-galactan side chains. These side chains are highly variable in length, from one to at least 20 Gal residues and are highly substituted with α-L-Araf. Single GlcA residues are also present at the non-reducing termini of some short β-(1→6)-galactan side chains. In addition, the β-(1→6)-galactan side chains are also substituted with β-L-Arap. We propose a polysaccharide structure of the wheat flour AGP that is substantially revised from earlier models.
School of Biological Sciences, Department of Biochemistry, Hopkins Building, The Downing site, Tennis Court Road, Cambridge University, CB2 1QW Cambridge, UK.
Theodora
T
Tryfona
Hui-Chung
HC
Liang
Toshihisa
T
Kotake
Satoshi
S
Kaneko
Justin
J
Marsh
Hitomi
H
Ichinose
Alison
A
Lovegrove
Yoichi
Y
Tsumuraya
Peter R
PR
Shewry
Elaine
E
Stephens
Paul
P
Dupree
D005433:Flour / Q000032:analysis*; D015394:Molecular Structure; D009088:Mucoproteins / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry; D014908:Triticum / Q000737:chemistry*
D009088:Mucoproteins; D010940:Plant Proteins; C006619:arabinogalactan proteins