Optimization Of Enzymatic Reaction And Physical Characterization Of Alkyl Glucosides

Tenβ-D-glucopyranosides were enzymatically synthesized through condensation of glucose with alcohols of varied alkyl chain length (C1-C1o). It was shown that the longer the alkyl chain, the lower the initial rate and the finial yield, except for methyl glucoside due to the severe toxicity of methanol to the enzyme. The yield of alkylβ-D-glucoside was limited by the thermodynamic equilibrium, which was verified by performing both the glucoside hydrolysis and the glucoside synthesis via reverse hydrolysis. The equilibrium of the enzymatic glucoside synthesis was altered to improve the final yield, through optimization of water content, cosolvent composition, glucose concentration, and reaction temperature. The equilibrium yield of decylβ-D-glucoside was increased from 1.9% to 6.1%, when the water content was reduced from 10% to 5%(v/v), using tert-butanol as a cosolvent and 0.10 M of glucose as substrate.Pentylβ-D-glucoside was used as the substrate to synthezed five novelβ-D-glucoside esters with fatty acid of vatious chain length catalyzed by Novozym 435. Their final yields were significantly affected by the alkyl chain length of acyl donors. The longer the alkyl chain, the lower the final yield.Physical characterazation of akylβ-D-glucosides and glucoside esters, such as optical rotation and the critical micelle concentration (cmc) were also investigated. Only those glucosides with long alkyl chain (>C6) show significant surface activity. The surface tension and cmc decreased greatly when the alkyl chain became longer.