Enhanced Glucose to Fructose Conversion in Acetone with Xylose Isomerase Stabilized by Crystallization and Cross-Linking

Abstract

The effects of acetone and ethanol on glucose to fructose conversion catalyzed by soluble and cross-linked crystalline (CLXIC) xylose isomerase were studied. Relative to pure buffer solvent, the fructose production rate was more than doubled in 50% acetone. The same kind of increase in the isomerization rate was not seen with ethanol. Increase both in acetone and in ethanol concentration in the reaction solvent enhanced the production of fructose. At 50 degrees C in pure buffer solvent the reaction mixture contained 49% fructose in equilibrium and in 90% acetone the fructose equilibrium content was 64%. Furthermore, CLXIC was relatively stable in the presence of high concentration of acetone: 70-80% of activity was left after incubation for 24 h at 50 degrees C in buffer solutions (pH 7.2) containing 10-90% acetone. In buffer containing 50% ethanol only 2% of the initial activity of CLXIC was retained after 24 h at 50 degrees C. Soluble xylose isomerase was considerably less stable than CLXIC in both acetone- and ethanol-containing solutions. These results show that the addition of acetone enhances the production of fructose from glucose by enhancing the reaction rate and shifting the equilibrium toward fructose. However, xylose isomerase must be in the form of cross-linked crystals for maximal activity and stability.

Novel type of two‐impinging‐jets reactor for solid–liquid enzyme reactions

“…Also, fructose is about 75% sweeter than sucrose, is absorbed more slowly than glucose, and is metabolized without the intervention of insulin. For all these reasons, this process is widely studied both with cells and with enzymes, both free and immobilized (IE) 1–13. From the perspective of chemical kinetics, isomerization of glucose to fructose is a reversible reaction, with an equilibrium constant of approximately unity at 55°C 14.…”

Production of furans from C5 and C6 sugars in the presence of polar organic solvents

“…30,33,34 This results in differences in the solvent-solute interaction, which also reflects on the reaction parameters, mechanism, and kinetics, with no possibility of forming glucosides. [107][108][109][110][111] Specifically, the presence of aprotic solvents in the mixture has been reported to promote the glucose-to-fructose isomerization (Scheme 2) and the formation of furanose-aldehyde intermediates (Schemes 1a and 2a). 107,111 The product/by-product distribution is also affected, largely increasing the selectivity of the dehydration of glucose and fructose towards HMF.…”

“…[107][108][109][110][111] Specifically, the presence of aprotic solvents in the mixture has been reported to promote the glucose-to-fructose isomerization (Scheme 2) and the formation of furanose-aldehyde intermediates (Schemes 1a and 2a). 107,111 The product/by-product distribution is also affected, largely increasing the selectivity of the dehydration of glucose and fructose towards HMF. 107 This specific behavior of aprotic solvents can be generalized to all dehydration reactions, with a direct effect on its mechanism, owing to competition between water and the polar organic solvent to form the solvent shell for the sugar, by interacting with its hydroxyl groups.…”

Whole-Genome Sequence of Stenotrophomonas maltophilia ZBG7B Reveals Its Biotechnological Potential

“…The S. maltophilia strain ZBG7B genome contains a repertoire of biodegradation-related genes, such as xylosidase (WP_042612111.1), which catalyzes the hydrolysis of xylose residues from the nonreducing ends of xylooligosaccharides ( 11 ); xylanase (WP_042612114.1), which depolymerizes xylan into monomeric pentosan ( 12 ); and xylose isomerase (WP_042612414.1), which catalyzes the interconversion of D -xylose and D-xylulose, as well as glucose to fructose ( 13 ). Furthermore, it also possesses laccase (WP_042613439.1), which is capable of decolorizing synthetic dyes ( 14 ), as well as chitinase (WP_042615338.1), which makes this strain a potential biocontrol agent against fungus ( 15 ).…”