Ketose 3-epimerase displayed an important role in not only the cyclic monosaccharides bioconversion strategy, named Izumoring, but also in the industrial biological production of d-psicose, a novel low-calorie rare sugar widely used in food and medical industries. Since the non-enzymatic side reactions could be reduced in acid conditions, slightly acidic pH optimum is one of the main issues for biological production of d-psicose.
Everything You Need to Know
What is an epimerase enzyme?
How can D-psicose be obtained from glucose?
The production of d-psicose from d-glucose requires the co-expression and synergistic action of xylose isomerase and d-psicose 3-epimerase.
What's the difference between epimerase and isomerase?
Isomerases are primarily employed to catalyze the isomerization between aldoses and ketoses, while epimerases facilitate the inversion of stereochemistry in sugar molecules with multiple chiral carbon atoms
What happens to glycogen if you don't eat carbs?
Not Eating Enough Carbohydrates
Low-carb or restrictive diets can significantly reduce glycogen stores. While some people tolerate lower carbohydrate intake well, others develop fatigue quickly. Your brain and muscles rely heavily on glucose. Without enough dietary carbohydrate, glycogen stores shrink.
Main Applications:
in the Food Industry
As the key biocatalyst for synthesizing D-psicose, it specifically catalyzes the epimerization of D-fructose at the C3 position to efficiently produce D-psicose.
Low-calorie sweetener production: D-psicose is an ideal sucrose substitute with approximately 70% of the sweetness of sucrose and only 10% of its calories, with no significant effect on blood glucose. It is widely used in beverages, confectionery, baked goods and other low-sugar health foods.
Food processing improvement: It promotes the Maillard reaction to enhance flavor and color in baked products, improves water-holding capacity and texture, and optimizes the clarity of juice products.
Functional food development: D-psicose has physiological functions such as inhibiting fat accumulation, regulating blood glucose and anti-inflammatory effects, so it is used in foods for people with obesity, diabetes and hyperlipidemia.
in Industrial Biotechnology
Biomass conversion: Participates in the pretreatment of agricultural waste such as corn stover and wheat bran, releases fermentable sugars, and improves the yield of bioethanol and bio-based chemicals.
Pulp and paper industry: Improves lignin extraction and bleaching efficiency, reduces the use of chemical bleaching agents and environmental pollution.
Biobased material synthesis: Catalyzes the production of sugar derivatives used as raw materials for degradable packaging and biological polymer materials.
in Medicine and Biomedicine
Rare sugar synthesis: Serves as a key tool enzyme for the preparation of D-psicose, D-tagatose and other rare sugars, which are important precursors for the research and development of anti-inflammatory, antioxidant and neuroprotective drugs.
Diagnostic reagents: Recombinant DPEase can be used as an enzymatic reagent for carbohydrate structure analysis and auxiliary detection of glycometabolism indicators.
ANALYTICAL RESULTS
| Test Item | Method / Reference | Informative Specification | Representative Result | Conclusion |
|---|---|---|---|---|
| Enzyme Name / Identity | EC database / ExPASy | D-Psicose 3-epimerase | EC 5.1.3.30; alternative names: D-allulose 3-epimerase, DPEase (Expasy ENZYME) | Conforms |
| Catalyzed Reaction | ExPASy enzyme entry | Reversible C-3 epimerization | D-allulose ⇌ keto-D-fructose (Expasy ENZYME) | Conforms |
| Substrate Specificity | ExPASy / UniProt | High specificity to D-psicose / D-fructose pair | Highly specific for D-psicose; very low activity with D-tagatose (Expasy ENZYME) | Conforms |
| Cofactor Requirement | Literature characterization / UniProt | Metal-dependent enzyme | Mn²⁺ preferred; Co²⁺ also active; Mg²⁺/Fe²⁺/Ni²⁺ show lower activity (Springer) | Conforms |
| Apparent Molecular Weight (Monomer) | SDS-PAGE / literature | ~30–33 kDa | Protein band observed at about 30 kDa; predicted size about 33 kDa (Springer) | Conforms |
| Quaternary Structure | Crystal structure literature | Tetrameric enzyme | Native enzyme reported as tetramer; each monomer belongs to TIM-barrel fold (RCSB PDB) | Conforms |
| Optimum pH | Enzymatic activity assay | Typically near neutral | Representative optimum pH = 7.5 (reported for recombinant food-production relevant examples) (Springer) | Conforms |
| Optimum Temperature | Enzymatic activity assay | Moderate thermal activity | Representative optimum temperature = 50–55°C (Springer) | Conforms |
| Recommended Mn²⁺ Level for Conversion | Process characterization | Low-mM level | 1 mM Mn²⁺ reported for IfDPEase; 10 mM Mn²⁺ reported for recombinant A. tumefaciens DPEase process optimization (MDPI) | Conforms |
| Representative Conversion Performance A | Literature process data | Informative only | At pH 7.5, 55°C, 10 mM Mn²⁺: 25% (w/v) fructose gave 5.60% (w/v) D-psicose; conversion rate 22.42% (Springer) | Informative |
| Representative Conversion Performance B | Literature process data | Informative only | At pH 7.5, 50°C, 1 mM Mn²⁺: 36.1% D-psicose obtained from 10 mg/mL D-fructose (MDPI) | Informative |
| Application Relevance | EFSA / industrial literature | Used for D-allulose production | Food enzyme preparations of D-psicose 3-epimerase are assessed for use in fructose-to-D-allulose isomerisation processes (efsa.onlinelibrary.wiley.com) | Conforms |
Production Process
