Tom Desmet
Ghent University, Belgium
Title: Exploring and engineering the application potential of sucrose transglycosidases
Biography
Biography: Tom Desmet
Abstract
Because of the growing health awareness among consumers, the sugar industry has come under severe pressure all over Europe. However, alternative valorization of common table sugar can be realized through its biocatalytic conversion into products with more attractive properties. In that respect, it should be noted that sucrose is a very powerful glycosyl donor with an unusually high energy content that enables product yields up to 80% to be reached. Several types of sucrose trans glycosidases can be found in family GH13, also known as the amylase-family. By exploring the properties of different family members, three new specificities could even be discovered. On the one hand, sucrose-6’-phosphate phosphorylase 1 points towards the existence of a new pathway for sucrose catabolism, involving an alternative Pts. On the other hand, a glucosyl glycerol 2 and glycosyl glycerate 3 phosphorylase provide new insights into the metabolism of compatible solutes. Subsequently, the most promising enzymes were engineered for the production of value-added compounds. Through iterative saturation mutagenesis, a double mutant was obtained with high selectivity (>95%) for Kojibiose (alpha-1,2-glucobiose) as product. This rare sugar shows potential as low-caloric and prebiotic sweetener but its large-scale application has previously been hampered by an exuberant price. In turn, by rationally expanding the size of the active site, a whole range of novel anti-oxidant glycosides could be synthesized in gram amounts. These products display improved solubility and stability, which should be beneficial for use in food or cosmetic formulations. Currently, several new enzymes and processes are being developed in the framework of the H2020-project “Carbafin”.