STRUCTURAL FEATURES OF THE POLYSACCHARIDE OF APRICOT GUM IN DEPENDENCE ON THE INFECTION WITH FUNGI, APPLICATION OF A SYNTHETIC MATERIAL AND VEGETATIVE PERIOD
At Chemical Institute, we investigated the structure of polysaccharides of plant gums, the apricot gum among them. We follow the structural properties of polysaccharides of apricot gum in dependence on the infection of the tree with pathogenic fungi and action of a chemical substance. We study the structural properties of these polysaccharides in dependence on the vegetative period as well.
Polysaccharide of the gum is isolated as follows. The gum is dissolved in such amount of distilled water that the resulting concentration of the solution of the gum is approximately 12%. The aqueous solution of the gum is poured into 3 volumes of acidified ethanol at vigorous stirring. To 1 liter of ethanol 10 ml of concetrated hydrochloric acid is added. The precipitate is filtered, washed with diluted acidified ethanol, diluted ethanol, ethanol (96%), and ether.
The polysaccharide of apricot gum (Prunus armeniaca, L.) isolated in such a way was homogeneous at electrophoresis and sedimetation in ultra-centrifuge. The polysaccharide was composed of 4-0-methyl-D-glucuronic acid, D-glucuronic acid, D-xylose, L-arabinose, D-galactose in a molar ratio of 0.6 : 1 : 0.3 : 3.2 : 3.2, and traces of D-mannose. Equivalent weight of the polysaccharide was 850 and molecular weight 192,000. The polysaccharide consumed 3.3 moles of periodate and released 0,33 moles of formic acid per equivalent. Methylation analysis gave the following methylethers (Tab. 1.).
On the basis of the obtained results we have designed the following average structural segment of the polysaccharide from apricot gum (Fig 1). The interior chain of the polysaccharide is composed of sequences of oligosaccharide A interrupted by L-arabinofuranose units which are also a branching point of short 4-0-methyl--D-glucuronopyranosyl-l → 6-D-galactose units. Oligosaccharide B also occurs in the interior chain besides the oligosaccharide