FP6 priority

1.1.1   Genomics and Biotechnology for Health

1.1.2

Title of the proposal

Preparation of biologically important oligo-saccharides by enzymic and chemoenzymic synthesis

Institute

Slovak Academy of Sciences, Institute of Chemistry
Dubravska cesta 9, 84238 Bratislava, Slovak Republic

Contact

Research subject for a potential FP6 project

Research subject for a potential FP6 project The research group is prepared to participate in the following scientific topics:
1) enzymic and chemoenzymic synthesis of oligosaccharides;
2) development of new biocatalysts.
In the first topic the group can contribute by synthesis of biologically important oligosaccharides:
i) by condensation reactions from free aldoses catalyzed by some glycosyl hydrolases;
ii) by glycosyl transfer reactions using glycosides and oligosaccharides as glycosyl donors catalyzed by retaining glycosyl hydrolases;
iii) employing glycosyl hydrolases transformed into glycosynthases by protein engineering technology (in collaboration with other molecular biology groups) from carbohydrate fluorides. The objective followed will be the introduction of new carbohydrate epitope into oligosaccharides and glycoconjugates as well as examination of the enzyme to modify solubility, reological properties and biological activities of polysaccharides due to enzymatic glycosylation. E.g., the epitopes containing galactosyl residues are important in immunology problems associated with organ transplatation.
In the second topic the group is expected to work towards discovery and exploration of the synthetic potential of new microbial hemicellulolytic enzymes. Considerable research capacity of the group is currently devoted to search for new hydrolytic enzymes degrading plant cell wall structures, both glycosyl hydrolases and esterases. One of such enzymes discovered by members of the Bratislava group are acetylxylan esterases, enzymes deacetylating plant polysaccharides. These enzyme not only deacetylate the corresponding polysaccharide but also show unique regioselectivity of deacetylation of various carbohydrates structures, an action which is completely different from that of other types of acetylesterases and lipases traditionally used in carbohydrate synthesis. The studies of acetylxylanesterases will afford new information on synthetic potential of this group of esterases. We have in mind particularly the selective blocking and deblocking of hydroxyl groups in saccharides needed for specific glycosylation reactions. The group has also ability to perform classical synthetic and structural carbohydrate chemistry.

Recent international cooperation of the research team

Inst. Microbiol., Academy of Sciences, Praha, Czech Republic (oligosaccharides) Technical University of Athens, Greece (esterases and oligosaccharides) United States Department of Sagriculture, Peoria, IL, USA (plant xylanolytic enzymes) State University of Ghent, Belgium (oligosaccharides and glycosides)

Proposer´s relevant publications related to the research subject

1. Biely P., Hirsch J., la Grange D. C., van Zyl W. H., Prior B. A. (2000):
A chromogenic substrate for a b-xylosidase-coupled assay of a-glucuronidase.Anal. Biochem. 286, 289-294.
2. Puchart V., Vrsanska M., Bhat M. K., Biely P. (2000):
Purification and characterization of a-galactosidase from a thermophilic fungus Thermomyces lanuginosus. Biochim.Biophys. Acta 1524, 27-37.
3.Biely P, Puchart V., Cote G. L. (2001):
Enzymic a-galactosylation of cyclic glucotetrasaccharide derived from alternan.Carbohydr. Res. 332, 299-303.
4. Mastihubova M., Biely P. (2001):
A common access to 2- and 3-substituted methyl b-D-xylopyranosides. Tetrahedron Letters 42, 9065-9067.