2.Production of sugar syrup containing rare sugar using dual-enzyme coupled reaction system.
Wenjia HAN ; Yueming ZHU ; Wei BAI ; Ken IZUMORI ; Tongcun ZHANG ; Yuanxia SUN
Chinese Journal of Biotechnology 2014;30(1):90-97
Enzymatic conversion is very important to produce functional rare sugars, but the conversion rate of single enzymes is generally low. To increase the conversion rate, a dual-enzyme coupled reaction system was developed. Dual-enzyme coupled reaction system was constructed using D-psicose-3-epimerase (DPE) and L-rhamnose isomerase (L-RhI), and used to convert D-fructose to D-psicose and D-allose. The ratio of DPE and L-RhI was 1:10 (W/W), and the concentration of DPE was 0.05 mg/mL. The optimum temperature was 60 degrees C and pH was 9.0. When the concentration of D-fructose was 2%, the reaction reached its equilibrium after 10 h, and the yield of D-psicose and D-allose was 5.12 and 2.04 g/L, respectively. Using the dual-enzymes coupled system developed in the current study, we could obtain sugar syrup containing functional rare sugar from fructose-rich raw material, such as high fructose corn syrup.
Aldose-Ketose Isomerases
;
metabolism
;
Carbohydrate Epimerases
;
metabolism
;
Fructose
;
chemistry
;
Glucose
;
chemistry
;
Hydrogen-Ion Concentration
;
Temperature
3.Bioconversion of D-fructose to D-allose by novel isomerases.
Wei BAI ; Yueming ZHU ; Yan MEN ; Xiaobo LI ; Ken IZUMORI ; Yuanxia SUN
Chinese Journal of Biotechnology 2012;28(4):457-465
Rare sugar is a kind of important low-energy monosaccharide that is rarely found in nature and difficult to synthesize chemically. D-allose, a six-carbon aldose, is an important rare sugar with unique physiological functions. It is radical scavenging active and can inhibit cancer cell proliferation. To obtain D-allose, the microorganisms deriving D-psicose 3-epimerase (DPE) and L-rhamnose isomerase (L-RhI) have drawn intense attention. In this paper, DPE from Clostridium cellulolyticum H10 was cloned and expressed in Bacillus subtilis, and L-RhI from Bacillus subtilis 168 was cloned and expressed in Escherichia coli BL21 (DE3). The obtained crude DPE and L-RhI were then purified through a HisTrap HP affinity chromatography column and an anion-exchange chromatography column. The purified DPE and L-RhI were employed for the production of rare sugars at last, in which DPE catalyzed D-fructose into D-psicose while L-RhI converted D-psicose into D-allose. The conversion of D-fructose into D-psicose by DPE was 27.34%, and the conversion of D-psicose into D-allose was 34.64%.
Aldose-Ketose Isomerases
;
metabolism
;
Bacillus subtilis
;
enzymology
;
Carbohydrate Epimerases
;
metabolism
;
Clostridium cellulolyticum
;
enzymology
;
Escherichia coli
;
metabolism
;
Fructose
;
metabolism
;
Glucose
;
metabolism