Structure and solution properties of tamarind-seed polysaccharide.
The major polysaccharide in tamarind seed is a galactoxyloglucan for which the ratios galactose:xylose:glucose are 1:2:25:2.8. A minor polysaccharide (2-3%) contains branched (1----5)-alpha-L-arabinofuranan and unbranched (1----4)-beta-D-galactopyranan features. Small-angle X-ray scattering experiments gave values for the cross-sectional radius of the polymer in aqueous solution that were typical of single-stranded molecules. Marked stiffness of the chain (C infinity 110) was deduced from static light-scattering studies and is ascribed partially to the restriction of the motion of the (1----4)-beta-D-glucan backbone by its extensive (approximately 80%) glycosylation. The rigidity of the polymer caused significant draining effects which heavily influenced the hydrodynamic behaviour. The dependence of "zero-shear" viscosity on concentration was used to characterise "dilute" and "semi-dilute" concentration regimes. The marked dependence on concentration in the "semi-dilute" region was similar to that for other stiff neutral polysaccharide systems, ascribed to "hyper-entanglements", and it is suggested that these may have arisen through a tenuous alignment of stiffened chains.
Gidley
M J
MJ
Unilever Research Laboratory, Great Britain.
Lillford
P J
PJ
Rowlands
D W
DW
Lang
P
P
Dentini
M
M
Crescenzi
V
V
Edwards
M
M
Fanutti
C
C
Reid
J S
JS
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D005936:Glucans; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010944:Plants / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry*; D014783:Viscosity; D014990:Xylans
D005936:Glucans; D011134:Polysaccharides; D014990:Xylans; C029353:xyloglucan