D-Psicose

Thermal stability is a limiting factor for effective application of D-psicose 3-epimerase (DPEase) enzyme. Recently, it was reported that the thermal stability of DPEase was improved by immobilizing enzymes on graphene oxide (GO) nanoparticles. However, the detailed mechanism is not known. In this study, we investigated interaction details between GO and DPEase by performing molecular dynamics (MD) simulations. The results indicated that the domain (K248 to D268) of DPEase was an important anchor for immobilizing DPEase on GO surface...

D-psicose 3-epimerase (DPEase) catalyzes the isomerization of D-fructose to D-psicose (aka D-allulose, a low-calorie sweetener), but its industrial application has been restricted by the poor thermostability of the naturally available enzymes. Computational rational design of disulfide bridges was used to select potential sites in the protein structure of DPEase from Clostridium bolteae to engineer new disulfide bridges. Three mutants were engineered successfully with new disulfide bridges in different locations, increasing their optimum catalytic temperature from 55 to 65 °C, greatly improving their thermal stability and extending their half-lives (t1/2 ) at 55 °C from 0...

Food manufacturers are under increasing pressure to limit the amount of free sugars in their products. Many have reformulated products to replace sucrose, glucose and fructose with alternative sweeteners, but some of these have been associated with additional health concerns. Rare sugars are 'monosaccharides and their derivatives that hardly exist in nature', and there is increasing evidence that they could have health benefits. This review aimed to scope the existing literature in order to identify the most commonly researched rare sugars, to ascertain their proposed health benefits, mechanisms of action and potential uses and to highlight knowledge gaps...

Bacillus subtilis is a commonly used commercial specie with broad applications in the fields of bioengineering and biotechnology. B. subtilis is capable of producing both biofilms and spores. Biofilms are matrix-encased multicellular communities that comprise various components including exopolysaccharides, proteins, extracellular DNA, and poly-γ-glutamic acid. These biofilms resist environmental conditions such as oxidative stress and hence have applications in bioremediation technologies. Furthermore, biofilms and spores can be engineered through biotechnological techniques for environmentally-friendly and safe production of bio-products such as enzymes...

The combined catalysis of glucose isomerase (GI) and D-psicose 3-epimerase (DPEase) provided a convenient route for the direct synthesis of D-allulose from d-glucose, whose cost is lower than d-fructose. In the present research, the weak activity of DPEase was the key rate-limiting step and resulted in the accumulation of d-fructose in engineered Bacillus subtilis. Then, the 5'-untranslated region (5'-UTR) structure of the mRNA translational initiation region was optimized for the precise control of DPEase expression...

This research aimed to enhance the physicochemical and antioxidant properties of dried whole longan fruit using Maillard reaction or non-enzymatic glycosylation (glycation) in a moist-dry-heating system at 60 °C with approximately 75% relative humidity for 5-50 days. During Maillard reaction, the browning index (BI) of the fruits increased significantly while lightless, redness and yellowness decreased. Interestingly, the rare sugars especially D-psicose and D-allose gradually increased by 2-3 folds when compared to the initial Maillard reaction...

Diet and exercise are the most effective approaches used to induce weight loss. D‑psicose is a low‑calorie sweetener that has been shown to reduce weight in obese individuals. However, the effect of D‑psicose on muscle cells under oxidative stress, which is produced during exercise, requires further investigation. The present study aimed to determine the effects of D‑psicose on C2C12 myogenic cells in vitro. Hydrogen peroxide (H2 O2 ) was used to stimulate the generation of intracellular reactive oxygen species (ROS) in muscle cells to mimic exercise conditions...

The food enzyme d-psicose 3-epimerase (EC 5.1.3.30) is produced with the genetically modified Escherichia coli strain K-12 W3110 (pWKLP) by Matsutani Chemical Industry Co., Ltd. The production strain of the food enzyme contains multiple copies of an antimicrobial resistance gene. However, based on the absence of viable cells and DNA from the production organism in the food enzyme, this is not considered to be a risk. The food enzyme is used as an immobilised preparation in processing fructose for the production of a speciality carbohydrate d-allulose (syn...

D-allulose is an epimer of D-fructose at the C-3 position. With similar sweetness to sucrose and a low-calorie profile, D-allulose has been considered a promising functional sweetener. D-psicose 3-epimerase (DPEase; EC 5.1.3.30) catalyses the synthesis of D-allulose from D-fructose. Immobilised enzymes are becoming increasingly popular because of their better stability and reusability. However, immobilised DPEase generally exhibits less activity or poses difficulty in separation. This study aimed to obtain immobilised DPEase with high catalytic activity, stability, and ease of separation from the reaction solution...

d-Psicose 3-epimerase (DPEase) can catalyze the isomerization of d-fructose to be rare sugar d-psicose, which has wide application prospects in the food and medical fields. In this study, the DPEase gene from Agrobacterium tumefaciens was constructed into plasmid pMA5, and was successfully expressed in the host Bacillus subtilis WB600 (B. subtilis). After optimization of the fermentation conditions, whole recombinant B. subtilis WB600/pMA5-At-DEPase(O) cells produced d-psicose from d-fructose with a conversion rate of 29...

The class EC 5.xx, a group of enzymes that interconvert optical, geometric, or positional isomers are interesting biocatalysts for the synthesis of pharmaceuticals and pharmaceutical intermediates. This class, named "isomerases," can transform cheap biomolecules into expensive isomers with suitable stereochemistry useful in synthetic medicinal chemistry, and interesting cases of production of l-ribose, d-psicose, lactulose, and d-phenylalanine are known. However, in two published reports about potential biocatalysts of marine origin, isomerases are hardly mentioned...

d-Psicose (d-ribo-2-hexulose or d-allulose) is the Carbon-3 epimer of d-fructose sugar and considered as an unnatural (rare) sugar found in low amount in nature. It has about 70% of the relative sweetness but 0.3% of the energy of sucrose, which is suggested as the most suitable sucrose substitute for food additives. Enzymatic biosynthesis using ketose 3-epimerases is a necessary procedure for the production of d-Psicose from d-fructose. However, significant drawbacks in the application of ketose 3-epimerases at industrial scale observe lower thermal stability as well as bioconversion efficiency, reusability and recovery of the enzyme...

Allitol is a kind of rare sugar alcohol with potential application value. An engineered strain, which simultaneously expressed D-psicose-3-epimerase (DPE), ribitol dehydrogenase (RDH), and formate dehydrogenase (FDH) three enzymes, was constructed by cloning above three genes into one plasmid and transformed into the host E. coli strain, and used as the whole-cell catalysts for biotransformation of allitol from the low-cost substrate of D-fructose. The whole cell allitol biotransformation conditions were optimized...

OBJECTIVE: To develop a method combining enzymatic catalysis and resting-cell biotransformation to produce allitol from low cost substrate D-glucose. RESULTS: The recombinant E. coli expressing D-psicose-3-epimerase (DPE), ribitol dehydrogenase (RDH) and formate dehydrogenase (FDH) for allitol production from D-fructose was constructed. The optimizations of the cell catalytic conditions and the cell cultivation conditions were made. Then, 63.4 g allitol L-1 was obtained from 100 g D-fructose L-1 in 4 h catalyzed by the recombinant E...

YcjR from Escherichia coli K-12 MG1655 catalyzes the manganese-dependent reversible epimerization of 3-keto-α-D-gulosides to the corresponding 3-keto-α-D-glucosides as a part of a proposed catabolic pathway for the transformation of D-gulosides to D-glucosides. The three-dimensional structure of the manganese-bound enzyme was determined by X-ray crystallography. The divalent manganese ion is coordinated to the enzyme by ligation to Glu-146, Asp-179, His-205, and Glu-240. When either of the two active site glutamate residues are mutated to glutamine the enzyme loses all catalytic activity for the epimerization of α-methyl-3-keto-D-glucoside at C4...

BACKGROUND AND OBJECTIVE: The DPEase enzyme from Agrobacterium tumefaciens is more efficient and has a high activity in D-fructose. The dpe gene has been successfully cloned to Escherichia coli BL21 (DE3) pET-21b dpe but the enzyme has not been purified and its character is unknown. The intent of this study was to purify and assign of DPEase enzyme by recombinant E. coli. MATERIALS AND METHODS: The enzyme was clarified by affinity chromatography and then characterized by following pH, temperature, co-factor parameters...

d-Psicose, as important rare sugar and epimer of d-fructose on the C-3 position, displays unique health benefits and physiological functions in various fields. The production of d-psicose is currently obtained via enzymatic bioconversion, mostly with of d-tagatose 3-epimerase. In the present study, the isomerization of d-fructose into d-psicose was achieved by constructing engineered food-grade Bacillus subtilis through fermentation. After optimizing the fermentation conditions of the recombinant strain, the yield of d-psicose reached up to 4...

A synthetic platform for the cascade synthesis of rare sugars using Escherichia coli whole cells was established. In the cascade, the donor substrate dihydroxyacetone phosphate (DHAP) was generated from glycerol by glycerol kinase (GK) and glycerol phosphate oxidase (GPO). The acceptor d-glyceraldehyde was directly produced from glycerol by an alditol oxidase. Then, the aldol reaction between DHAP and d-glyceraldehyde was performed by l-rhamnulose-1-phosphate aldolase (RhaD) to generate the corresponding sugar-1-phosphate...

Ribose-5-phosphate isomerase B is of great interest for biocatalysis and biosynthesis, but the multifunctional residues in active sites hinder the research efforts. This study employed rational design strategies to locate key residues of RpiB from Ochrobactrum sp. CSL1 (OsRpiB). A single mutant S9T of a noncontact residue showed 80% activity improvement towards D-allose. A double mutant S98H/S134H further increased the activity to 3.6-fold. The mutations were analyzed by kinetics and molecular dynamics analyses, finding S9T might enhance the substrate binding and catalysis by inducing a steric effect, and S98H/S134H could strengthen both ring opening and binding of D-allose...

Dihydroxyacetone phosphate (DHAP)-dependent aldolases demonstrate important values in the production of rare ketoses due to their unique stereoselectivities. As a specific example, we developed an efficient Escherichia coli whole-cell biocatalytic cascade system in which rare ketoses were produced from abundant glycerol and catalyzed by four enzymes based on L-rhamnulose-1-phosphate aldolase (RhaD). For the semicontinuous bioconversion in which D-glyceraldehyde was continuously added, once D-glyceraldehyde was consumed, the final yields of D-sorbose and D-psicose were 15...