PhD. Topics

Enzymatic degradation of complex corn fibre xylan

Biochemistry

Mgr. Vladimír Puchart, PhD.

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Faculty of Natural Sciences, Commenius University Bratislava

All types of plant xylan are heteropolysaccharides comprising D-xylose-based backbone, which is decorated by a variety of substituents. The nature of the substituents, their frequency and distribution along the main chin is species-, tissue- and season-specific. The structure as well as enzymatic degradation of hardwood acetylglucuronoxylan and cereal arabinoxylan are well known. In contrast, the fine structure of heavily decorated corn fibre xylan including the presence of unique side chains still remains to be established . Similarly, its enzymatic degradation is only poorly resolved, that partially results from its resistance to the most common xylanases efficiently acting on glucuronoxylan and arabinoxylan. Although recently the xylanases depolymerizing the recalcitrant corn fibre xylan have been discovered, their mode of action and the eptopes recognized within the polysaccharide are still enigmatic. Moreover, du to the presence of unique side chains, their removal is expected to be catalyzed by novel enzymes awaiting their discovery. Looking up and characterization of the new enzymes participating in enzymatic breakdown of the recalcitrant corn fibre xylan will be the topics of the postgraduate study.
Aims: 1. To search for novel, hitherto unknown enzymes that take part in the degradation of heavily substituted corn fibre xylan; 2. To study in detail catalytic properties of known, but insufficiently characterized enzymes degrading heavily substituted corn fibre xylan; 3. To establish a relationship between catalytic properties of these enzymes, their structure and the role in enzymatic degradation of complex xylans