Presentation on theme: "DEPARTMENT OF ENZYMOLOGY OF CARBOHYDRATES HEAD: Peter Biely CO-WORKERS: Mária Vršanská, Mária Cziszárová, Vladimír Puchart, Katarína Kolenová, Silvia Špániková,"— Presentation transcript:
DEPARTMENT OF ENZYMOLOGY OF CARBOHYDRATES HEAD: Peter Biely CO-WORKERS: Mária Vršanská, Mária Cziszárová, Vladimír Puchart, Katarína Kolenová, Silvia Špániková, Miroslava Křupalová
Research Direction Investigation of processes of microbial degradation of plant cell walls – a part of the carbon cycle Research is closely related to: Development of economically feasible and enviromentally friendly processes of bioconversion of renewable lignocellulose biomass to useful products Introduction of enzymatic technologies in the pulp and paper industry, food industry and agriculture Preparation of functional food additives on the basis of plant polysaccharides
Main Focus Enzymatic degradation of plant hemicelluloses: xylans and galactoglucomannans, plus linkages carbohydrates-lignin Search for new enzymes and novel catalytic activities – number of covalent linkages in plant cell walls is larger than the number of so far described enzymes Regulatory aspects of the formation of hydrolytic enzymes (glycosyl hydrolases, esterases) in microorganisms, enzyme isolation, properties, mode of action Application of glycosyl hydrolases and esterases as biocatalyst for synthesis of new biologically and nutritionally important carbohydrate derivatives
Example of Hypothetical Plant Xylan and Enzymes of Its Hydrolysis PhA (Fe, p-Coum) Araf Araf Ac 1 1 3 ( ) 3 ( ) 3 Xyl 1-4Xyl 1-4Xyl 1-4Xyl 1-4Xyl 1-4Xyl 1-4Xyl 1-4Xyl 1-4Xyl 1-4Xyl 1-4Xyl 1-4Xyl 1-4Xyl -4Xyl 1- 2 2 2 1 Ac 1 MeGlcA MeGlcA endo- -1,4-xylanase (EC 220.127.116.11) -xylosidase (EC 3.2.1..37) or exo- -xylanase Xyl 1-4Xyl 1- -glucuronidase (EC 18.104.22.168) -L-arabinofuranosidase (EC 22.214.171.124) feruloylesterase or p-coumaroylesterase (EC126.96.36.199) acetylxylan esterase (EC 188.8.131.52) Enzyme described first by members of the Department (1985) members of the Department (1985) Major depolymerizing enzyme and its inhibitors– receive main attention
Industrial Applications of Endoxylanases Successful biotechnologies of the last decade Pulp and paper industry (cellulase-free xylanases) – bleaching of kraft pulp – reduction of toxic chemicals needed for lignin extraction Animal diet –hydrolysis of highly viscous arabinoxylans – improvement of digestibity of fodders based on cereals Bakery – improvement of dough handling by decreasing viscosity of arabinoxylans in flour – change in the quality of baked products Preparation of xylooligosaccharides – functional food additives, prebiotics, moisture preserving compounds
Examples of Reverse Enzymatic Reactions Acetylation of carbohydrates in microemulsions with a fungal acetylxylan esterase (2004) Unique regioselective acetylation of oligosaccharides by fungal hemicellulolytic acetyl esterase in water-vinyl acetate mixtures (2005) -Galactosylation of internal linkages of oligosaccharides (e.g. β-1,4-Man 5 ) by a fungal -galactosylase: Gal donor 4- nitrophenyl -Galp (2005) Cellopentaose - position O-3 of the non-reducing residue
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