Pectin polysaccharides (PSs) were isolated from a bark of Larix sibirica Ledeb. Structure of PS fragments determined by chemical transformations, chromatography, and spectroscopic analyses was found to be a linear galacturonane comprising 1,4-linked α-D-GalpA residues and a rhamnogalacturonan I (RG-I). The fifth part of galacturonane residues was methyl esterified at at C-2 and/or C-3 and C-6 atoms. Some of RG-I side chains were identified as arabinogalactan subunits with highly branched structure consisting of linear backbone with 3,6)-β-D-Galp-(1 residues, substituted at C-6 by neutral side chains. This side chains contained 2,5)-α-L-Araf-(1 and 3,5)-α-L-Araf-(1 residues and terminal arabinose in the pyranose and furanose form. It was found that “pectin-Ag(0)” nanobiocomposites were formed via the interaction between PS aqueous solutions and silver nitrate, with PS playing both reducing and stabilizing functions. It was shown that the content of Ag(0) particles in “pectin-Ag(0)” depended on the reaction conditions and can range from 0.1 to 72 %, the size of Ag(0) particles being 3–27？nm. Using 13C NMR technique, it was revealed that PS underwent destructive changes and they they were more considerable, more than the lot of Ag(I) that was inputed into the reactionary medium. 1. Introduction Two species of the genus Larix Mill, Larix sibirica Ledeb and Larix gmelinii (Rupr.) Rupr., are considered to be the most abundant trees in the Russian Federation and the total stock of their wood recourses exceeds 26 billion？m3. Traditionally, the main economic benefit of the larch wood is a manufacture of roundwood (timber), the value of which is determined by a high quality of lumber obtained from this tree. Sometimes, the larch wood can be used in insignificant quantities in pulp-and-paper manufacture to produce pulp. Currently, about 40% of this valuable wood (bark, sawdust) is utilized as wastes. Such inexpedient approach to the utilization of larch wood does not allow using the richest potential of this renewable raw material. Meanwhile, biologically active compounds contained in larch biomass can be successfully applied for the manufacture of medical, food, and agricultural products. The development of complex technologies for chemical processing of larch biomass and waste timber will considerably raise the economic value of this biological resource. However, the larch bark does not find industrial application. Annual volume of waste produced by wood-processing industry and the pulp-and-paper enterprises is more than 30 million？m3. It represents a serious
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