Lawrence Novellie

Structural studies on a glucuronoarabinoxylan from the husk of sorghum grain

Abstract Polysaccharide H-3 is composed of L -arabinose, D -xylose, glucuronic acid, and 4-O-methylglucuronic acid in the molar ratios of 15:18:2:1. The polysaccharide contains a primary chain of α- D -(1→4)-linked D -xylopyranose residues. The identification of 2-O-(glucopyranosyluronic acid)- D -xylose and 2-O-(4-O-methylglucopyranosyluronic acid)- D -xylose revealed that the acid residues are bonded through O-2 of some D -xylopyranose moieties. Most of the L -arabinofuranose residues occur as nonreducing end-groups, attached through O-3, and in some cases through both O-2 and O-3, of certain D -xylose residues. Some L -arabinofuranose residues are substituted at O-2 or O-3. P.m.r. spectroscopy suggested that most of the L -arabinose units are α-linked.

A hemicellulosic β-D-glucan from the endosperm of sorghum grain☆

Abstract A hemicellulosic β- D -glucan of d.p. ≈26 has been isolated from the endosperm of sorghum grain. Methylation analysis, partial hydrolysis with acid, and periodateoxidation studies showed that the glucan is linear and has both (1 → 3)- and (1 → 4)-linked D -glucopyranose residues in the ratio of 3:2. The low, positive, specific rotation and chromium trioxide oxidation studies indicated that the D -glucose residues are β-linked.

Extraction of Sorghum vulgare and hordeum vulgare α-glucosidase

Abstract Sorghum and barley grain α-glucosidase are both insoluble in water. They are, nevertheless, active in the insoluble state. Limited extraction of the

A heteroxylan from the husk of Sorghum grain

Polysaccharide H-1 from the husk of Sorghum bicolor contains xylose, arabinose, glucose, galactose, glucuronic acid and 4-O-methylglucuronic ac

Structural studies on the water-soluble gums from the endosperm of sorghum grain

Abstract Purification by Bio-Gel P-100 chromatography of the cold-water-soluble gum from the endosperm of sorghum grain gave an electrophoretically homogeneous d -glucan. This polysaccharide (glucan A) had [α] d 20 + 88° and d.p. 23. Methylation analysis and periodate-oxidation studies indicated that glucan A has both (1→4)- and (1→6)-linked d -glucopyranose residues, in the ratio of 2:1. On average, three d -glucose residues per molecule of glucan A are branched. Chromium trioxide oxidation analysis of glucan A indicated a preponderance of α- d -glucosidic linkages. P.m.r. spectroscopy of permethylated glucan A showed the presence of α- and β-linkages in the ratio of 4:1. Purification of the hot-water-soluble gum by Bio-Gel P-100 chromatography gave glucan B, having [α] d 20 + 134° and d.p. 20. Structural studies showed glucan B to be similar to glucan A, differing in the ratio of (1→4)- to (1→6)-linkages; glucan B has these d -glucosidic linkages in the ratio of 6:1.

Lytic bodies from cereals hydrolysing maltose and starch

Abstract Protein bodies and spherosomes from sorghum contained carbohydrase activity against maltose, starch and p -nitrophenyl-α- d -glucoside. Maltase activities in sorghum and also in maize lytic bodies were very high; carbohydrase activities of lytic bodies from whole wheat, whole barley, sorghum aleurone, sorghum embryo and maize embryo were considerably lower. The pH response of sorghum lytic bodies was bimodal with an optimum in the range of 3·4–4·2 and a minimum or a shoulder near pH 3·8. Protein bodies from sorghum, maize, wheat and barley reduced the iodine-colouring capacity of soluble starch to give a purple colour typical of a β-limit dextrin. With spherosomes colour reduction was usually more rapid, eventually taking the breakdown of starch beyond the achroic point. The lytic bodies produce both maltose and glucose from starch, except in the case of maize when only glucose was found. The data suggest that protein bodies contain a linked β-amylase-maltase system and that spherosomes contain a linked α-amylase-maltase system.

DMSO-soluble hemicelluloses from the husk of Sorghum grain

Abstract The chlorite holotellulose from the grain husk of Sorghum bicolor was extracted with DMSO and the hemicellulosic material separated into water-solu

Structural studies on three hemicellulose B fractions from the husk of sorghum grain

Abstract Hemicelluloses H-4, H-8, and H-9 each contains L -arabinose, D -xylose, D -galactose, D -glucose, glucuronic acid, and 4- O -methylglucuronic acid. The degrees of polymerization of these polysaccharides are 993 (H-4), 2,380 (H-8), and 851 (H-9). These polysaccharides have backbones of β-(1→4)-linked D -xylopyranosyl residues to which are attached side chains of L -Arabinofuranosyl or glucosyluronic acid groups. L -Arabinofuranosyl groups are attached at O-3, or O-2 and O-3, of certain D -xylopyranose residues. Glucosyluronic acid side-chains are attached to the primary xylan chain at O-2 of some D -xylose residues. Hemicelluloses H-4, H-8, and H-9 differ from one another in their degree of branching.

Extraction of a salt-insoluble α-glucosidase from Sorghum vulgare grain

Abstract Sorghum grain α-glucosidase may be either insoluble in sodium chloride under alkaline conditions, or partially soluble, depending upon the sorghum variety. A good correlation was found between the degree of sodium chloride insolubility of the grain α-glucosidase and the degree of water-insolubility of the malt amylases. Peptone, in the presence of sodium chloride, was effective in liberating sodium chloride insoluble α-glucosidase from grain. Similarly, the water-insoluble amylases of malt were solubilized by peptone in water. Maximum liberation of grain ga-glucosidase was only achieved, however, by using a combination of 8 M urea, 0·1 M sulphite, 5% peptone and 1% Triton. It is suggested that the insolubility in both enzymes is caused by insoluble tannin-enzyme complexes.