The Constitution of a Hemicellulose From Sugar Maple (Acer Saccharum)

Abstract

Partial hydrolysis of the main hemicellulose constituent of sugar maple (ilcer saccharntlz) has yielded D-xyloSe, D-galacturonic acid, 4-0-methyl-D-gl~rcuronic acid, and 2-0-(4-0-methyla-D-glucosyluronic acid)-D-xplose. Hydrolysis of the fully methylated polysaccharide gave a mixture of 2-0-and 3-O-methyl-D-xylose, 2,3-di-0-n1ethyl-~-xylose, 2,3,4-tri-O-methyl-~-xplose, and 2-0-(2,3,4-tri-0-n~etl~yl-a-~-gl~1cosyluronic acid)-3-0-methyl-D-sylose in a mole ratio of 3 : 111 : 1 : 12. The number-average degrees of polymerization of the native and the lnethylated polysaccharide were 205 and 149, respectively. These data indicate that the hemicellulose is composed of a linear chain of 1,4-linked P -D -x~~o s~ residues and that on the ax-erage every tenth residue of the chain carries a ternlinal 4-O-methyl-~-glucuronic acid residue attached through its C?. The structure of tile polysaccharide is similar to that of the main hernicellulose component of European beech, \\,bite birch, and yello\\-birch.Sugar maple is an inlportani hardwood species in the lort the astern part of this continent. Ritter and co-worlcers (1, 2) have st~idied the general conlposition of various he~nicellulose fractions from this wood and chromatographic evidence for the presence of 4-0-methyl glucuronic acid has been reported by Nelson and Schuerch (3). The structure of the same hemicellulose has been s t~~d i e d by Neubauer and Purves (4), who concluded that the polysaccharide ~7 a s composed of a branched baclcbone of 1,4-linked xylose residues, some of which carried terrniiial 0-methyl glucuro~~ic acid residues. I n a previous investigation (5) the molecular properties of a native cellulose from sugar maple were studied. The present paper is concerned with the constitution and properties of the main heniicellulose component of this species. RESULTS AKD DISCIiSSIONThe high pentosan content of the \vood (18.5%) indicated that the preponderant l~emicellulose \vas a xylan. When the mood was extracted wit11 alkali, a heinicellulose was obtained in a yield of 12.4%, giving D-x).~os~ and three uronic acid compounds on partial hydrolysis. The sugar acids were separated from the xylose oil ail anion exchange resin and the mixture obtained was resolved on a charcoal coluil~n to yield galacturonic acid, 4-0-illethyl gluc~~ronic acid, and an aldobiouronic acid. T h e hexuro~iic acids were identified cI~ron1atographical1~-whereas the structure of the aldobiouronic acid was proved by the following experiments.Reduction of the methyl glycoside methyl ester of the alclobiouro~iic acid followecl by l~ydrolysis gave D -X J~~O S~ and 4-0-methyl-D-glucose. When the neutral disaccharide was methylated to completion and hydrolyzed, :-1,4-di-0-rneth~~l-~-xylose and 2,3,4,6-tetra-0-niethyl-D-glucose were obtained. This evidence, together with the specific rotation of the compound (+100°) (G), sholvecl that the acid was 2-0-(~-O-1nethyl-or-~-~~1cosyluro1lic acid)-D-xylose.;\lIethanolysis of the fully methl.lated hemicell~ilose gave a inixture of glycosides...

A Metataxonomic Analysis of Maple Sap Microbial Communities Reveals New Insights Into Maple Syrup Complexity

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Fourier Transform Infrared Spectroscopy for Natural Fibres

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Oligosaccharides From the Sap of Sugar Maple (Acer Saccharum Marsh)

“…They bear 110 resemblance in either co~nposition or I structure to the polysaccharides found in the sap ( G ) a~~c l wood of the sugar maple (25,26). These latter polysaccharides must have their origin from precursors unrelated to the sap oligosaccharides.…”