Effects of Organic Solvents on Acceptor Reactions for Oligosaccharide Synthesis Catalyzed by Glucansucrase URE 13-300

Glucansucrases from GH70 family are effective transglucosylases, able to use non-carbohydrate acceptors. Glycosylation of flavonoids or terpenoids increases their water-solubility and bioavailability. Enzymatic glycosylation by glucansucrases can be improved by addition of organic solvents to the reaction media. Thus, the aim of the study was to assess effects of menthol, carvacrol and thymol solubilized in organic solvents on the activity of glucansucrase URE 13-300 and transferase reaction.

Several organic solvents were assessed for their effects on glucansucrase activity using DNS method. Kinetic parameters in presence of the most appropriate solvents were evaluated as well. Thymol, carvacrol and menthol were solubilized in DMSO and their effects on the enzyme activity was assessed. Dynamic of oligosaccharides synthesis in aqueous-organic media was investigated using high-performance liquid chromatography.

Maltose-derived oligosaccharides synthesized by glucansucrase URE 13-300 showed degrees of polymerization from 3 to 6 in presence of organic solvents, as well as in presence of buffer alone. Their concentrations did not differ significantly in each of the reactions in aqueous-organic media. Furthermore, kinetic parameters showed adjacent Km values with 5% solvents compared to the control reaction in buffer. These findings revealed that the overall synthesis of glucooligosaccharides was not altered by the organic solvents, nevertheless they changed the product distribution throughout the transferase reactions. These moderate effects of the selected organic solvents were important requirement for the glycosylation of biologically active compounds for use in the food industry.