Structural features of two amyloids from the hemicellulosic fraction of field bean (Dolichos lablab) hulls.

Two amyloid-type fractions were isolated from field-bean (Dok~zos Zablab)
hdls by 10 % alkali extraction followed by acetylation and solvent fractionation. The
major, chloroform-insoluble fraction and a minor, chloroform-soluble fraction were
found to be homogeneous in sedimentation analysis and molecular-sieve chromatography_
The polysaccharides contained xylose and glucose in various proportions_
Methylation analysis, periodate oxidation, Smith degradation, oxidation by chromium
trioxide, and oligosaccharide studies indicated a new type of structure for the major
fraction (glucose:xylose ratio of 1.9 : 1) in that it had a backbone of (144)-linked
&D-glucose residues interspersed with single or multiple residues of (1+4)-linked
b-D-xylose, and to which some single D-xylosyl groups are attached through O-6 of
D-glucose. In contrast, the minor fraction (glucose: xylose ratio of 1 : 3.7) had a
backbone of (l-+4)-linked p-D-xylose interspersed with (1-4)~/?-D-glucose and having
a side chain of D-xylose, attached through O-6 of D-glucose. The third fraction was
found to be a mixture of linear (1+4)-D-glucan and (1+4)-o-xylan.