|Auteur:||M. ter Wal|
|D.Petrovic at rug.nl|
(Oligo)cellulose synthesis by enzymatic polymerization
Polysaccharides are an abundant source of raw materials that are interesting due to their biocompatible and renewable characteristics. Glycoengineering has attracted much attention from chemical, biological and medical standpoints. However, conventional chemical synthetic approaches are inadequate to provide large quantities of cellulose and other polysaccharides. Biosynthesis of polysaccharides is very attractive approach as it has many advantages such as: mild reactions conditions, high enantio-, regio- chemoselectivity and nontoxic natural catalysts (enzymes).
The aim of this research is to enzymatically synthesize (oligo)cellulose using cellobiose phosphorylase (CbP) and/or cellodextrin phosphorylase (CdP) enzymes. CbP and CdP enzymes reversibly catalyze phosphorolysis of cellobiose and cellodextrins into glucose-1-phosphate (G1P) and glucose or cellodextrins with reduced chain length, respectively. Because of the reversible nature of phosphorolytic reactions, CbP and CdP enzymes can also be used in the synthesis of cellobiose and (oligo)cellulose, respectively (figure 1).
Cellodextrin chains containing more than ~8 glucose units are known to have low solubility level in aqueous solutions. Therefore in vitro synthetic approaches, using CbP and CdP enzymes in aqueous solutions result in low degrees of polymerization. Big part of our work aims to increase the degree of polymerization of the obtained (oligo)cellulose by using advanced solvent systems such as ionic liquids (ILs). ILs are composed entirely of ions and are liquid at room temperature and able to dissolve many compounds, among them cellulose. Not all enzymes are suitable for catalysis in ILs. Therefore this research also includes development of new enzymes using chemical modification or molecular biology techniques (such as random mutations or rational design) which will be more suitable for this type of polymerization catalysis.
The synthesized products (oligo)cellulose) will be characterized by standard techniques for carbohydrates such as size exclusion chromatography (SEC), viscosimetry and matrix-assisted laser desorption – time of flight mass spectrometry (MALDI-ToF MS).
|Laatst gewijzigd:||01 juli 2015 10:53|