PLANT POLYSACCHARIDE XYLOGLUCAN AND ENZYMES THAT HYDROLIZE IT (REVIEW)

Various types of plant raw material are widely used in the pulp and paper, textile, food, agricultural industries, and pharmacology. One of the problems of utilizing the complex plant biomass is the weak knowledge of its hemicellulose content and the lack of effective enzymes for hydrolysis of hemicelluloses. Xyloglucan is the major structural and storage polysaccharide in all dicots and many monocots. It has a branched architecture with a backbone constructed of β-1,4-connected cellotetraose units decorated with short side chains composed of xylose, galactose, arabinose, fucose and some other residues. Side chain composition and alternation order are specie-specific and can change during cell growth resulting in variety of xyloglucan structural types. In general, xyloglucan structure depends on taxonomic position of the plant. Structural features of xyloglucans belonging to different taxonomic groups are discussed in the evolutionary aspect. Xyloglucan hydrolysis is a necessary condition during conversion of plant biomass into high added value products. Variety of xyloglucan structural types complicates selection of enzymes for its hydrolysis. Xyloglucanase-containing multienzyme complexes can be used for efficient decomposition of plant biomass polysaccharides into fermentable sugars for biotechnology, and for improvement of the feed quality. Investigation of xyloglucanases is necessary for the development of methods for protecting plants from pathogenic microorganisms which use these enzymes for invasion into plant tissue. The article reviewed structural features of xyloglucans from different taxonomic groups in the evolutionary aspect. Selection of xyloglucanases for efficient hydrolysis of complex plant biomass is discussed.