GO:0050571 1,5-anhydro-D-fructose reductase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0050571 (1,5-anhydro-D-fructose reductase activity) catalyzes the NADPH-dependent reduction of 1,5-anhydro-D-fructose to 1,5-anhydro-D-glucitol, the reverse of the reaction described in the QuickGO definition.
• The enzyme was first purified from mammalian liver as an NADPH-dependent reductase that specifically acts on 1,5-anhydro-D-fructose.
• In primates, dimeric dihydrodiol dehydrogenase (DDH) functions as an efficient 1,5-anhydro-D-fructose reductase, linking this activity to a multifunctional aldo-keto reductase.
• Bacterial enzymes such as levoglucosan dehydrogenase catalyze related oxidation-reduction reactions on anhydro sugars, providing evolutionary and structural context.
• 1,5-anhydro-D-fructose and its reduction product 1,5-anhydro-D-glucitol are involved in adipogenesis inhibition and inflammatory signaling, suggesting metabolic and immunomodulatory roles.
• The activity is relevant to carbohydrate metabolism, diabetes biomarker research, and the development of CRISPR-engineered cell models for functional validation.
Description
1,5-anhydro-D-fructose reductase activity (GO:0050571) is a molecular function defined by the reversible NADPH-dependent interconversion of 1,5-anhydro-D-fructose and 1,5-anhydro-D-glucitol. This activity sits at the intersection of carbohydrate metabolism and redox biology, and it has attracted attention because 1,5-anhydro-D-glucitol is a clinically used marker of glycemic control, while 1,5-anhydro-D-fructose displays biological activities in adipocytes and inflammatory models. The enzyme was initially purified from mammalian liver as a reductase that specifically acts on 1,5-anhydro-D-fructose, establishing the biochemical basis for the GO term. Subsequent work identified dimeric dihydrodiol dehydrogenase as an efficient primate 1,5-anhydro-D-fructose reductase, expanding the known protein families capable of this activity. In bacteria, related anhydro-sugar oxidoreductases such as levoglucosan dehydrogenase have been structurally and functionally characterized, offering comparative insights into catalysis and substrate recognition. For researchers, GO:0050571 provides a precise annotation for functional genomics, enzyme engineering, and metabolic disease studies. Understanding its mechanism, regulation, and disease links is essential for interpreting omics data and for designing CRISPR-based experiments that test causality.
1,5-anhydro-D-fructose reductase activity At A Glance
| GO ID | GO:0050571 |
|---|---|
| GO term | 1,5-anhydro-D-fructose reductase activity |
| Ontology | molecular_function |
| Synonym | 1,5-anhydro-D-glucitol:NADP+ oxidoreductase activity; AF reductase activity |
| Definition | Catalysis of the reaction: 1,5-anhydro-D-glucitol + NADP+ = 1,5-anhydro-D-fructose + H+ + NADPH |
| Major function | NADPH-dependent reduction of 1,5-anhydro-D-fructose to 1,5-anhydro-D-glucitol |
| Cofactor | NADPH / NADP+ |
| Representative enzyme | Dimeric dihydrodiol dehydrogenase (primate); hepatic AF reductase |
| Related activity | Levoglucosan dehydrogenase (bacterial anhydro-sugar oxidoreductase) |
What Is GO:0050571?
In simple terms, GO:0050571 describes an enzyme activity that uses NADPH to reduce 1,5-anhydro-D-fructose to 1,5-anhydro-D-glucitol, or catalyzes the reverse oxidation depending on cellular conditions. The QuickGO definition states: Catalysis of the reaction: 1,5-anhydro-D-glucitol + NADP+ = 1,5-anhydro-D-fructose + H+ + NADPH. This places the activity among oxidoreductases acting on CH-OH groups of donors with NADP+ or NADPH as acceptor. Synonyms include 1,5-anhydro-D-glucitol:NADP+ oxidoreductase activity and AF reductase activity. The reaction is reversible in principle, but the physiological direction depends on substrate availability and the NADP+/NADPH ratio. The enzyme was first described as a hepatic NADPH-dependent reductase specific for 1,5-anhydro-D-fructose, and later shown to be catalyzed efficiently by dimeric dihydrodiol dehydrogenase in primates.
Why Is 1,5-anhydro-D-fructose reductase activity Important in Cell Biology?
GO:0050571 is important because it connects a specific redox reaction to clinically relevant metabolites. 1,5-anhydro-D-glucitol is a widely used serum biomarker for short-term glycemic control, and its levels depend on the balance between dietary intake, renal handling, and enzymatic interconversion with 1,5-anhydro-D-fructose. The reductase activity therefore influences the steady-state concentration of this biomarker. In addition, 1,5-anhydro-D-fructose has been reported to inhibit adipogenesis in 3T3-L1 adipocytes and to attenuate LPS-induced iNOS expression, suggesting roles in metabolic and inflammatory regulation. The identification of dimeric dihydrodiol dehydrogenase as an efficient primate 1,5-anhydro-D-fructose reductase links this activity to the aldo-keto reductase superfamily, which is involved in drug metabolism and detoxification. Bacterial homologs such as levoglucosan dehydrogenase provide structural templates for understanding catalysis and for biotechnological applications. For researchers, precise annotation of GO:0050571 enables accurate functional interpretation of transcriptomic and proteomic data and supports the design of CRISPR models to test causality.
• Provides a molecular explanation for the interconversion of 1,5-anhydro-D-fructose and 1,5-anhydro-D-glucitol, a clinically used glycemic marker.
• Links carbohydrate metabolism to the aldo-keto reductase superfamily via dimeric dihydrodiol dehydrogenase.
• Supports studies on adipogenesis inhibition by 1,5-anhydro-D-fructose in 3T3-L1 cells.
• Relevant to inflammatory signaling, as 1,5-anhydro-D-fructose attenuates LPS-induced iNOS expression.
• Provides a target for enzyme engineering and biocatalysis of anhydro sugars.
• Enables comparative studies with bacterial levoglucosan dehydrogenase and other anhydro-sugar oxidoreductases.
• Helps interpret omics data by assigning a precise GO term to candidate genes.
• Facilitates CRISPR knockout and knock-in models to test the role of AF reductase in metabolic and inflammatory phenotypes.
• Contributes to understanding of seed germination and fruit ripening, where 1,5-anhydroglucitol levels change.
• Offers a potential node for diabetes and metabolic syndrome research through modulation of 1,5-anhydro-D-glucitol levels.
Molecular Mechanism of 1,5-anhydro-D-fructose reductase activity
Substrate recognition and binding
In simple terms: The enzyme grabs 1,5-anhydro-D-fructose and holds it in place so it can be reduced.
The hepatic NADPH-dependent reductase was purified based on its specific action on 1,5-anhydro-D-fructose, indicating a defined substrate-binding pocket that discriminates this anhydro sugar from related hexoses. In primates, dimeric dihydrodiol dehydrogenase also binds 1,5-anhydro-D-fructose efficiently, suggesting that the substrate can be accommodated by aldo-keto reductase folds. Bacterial levoglucosan dehydrogenase, which acts on a structurally related anhydro sugar, provides a structural framework for understanding how such substrates are recognized.
Catalytic reduction and cofactor usage
In simple terms: NADPH donates electrons to convert the sugar into its alcohol form.
The reaction catalyzed by GO:0050571 uses NADPH as the electron donor to reduce the carbonyl group of 1,5-anhydro-D-fructose, yielding 1,5-anhydro-D-glucitol and NADP+. The reverse reaction, oxidation of 1,5-anhydro-D-glucitol to 1,5-anhydro-D-fructose, is catalyzed by bacterial membrane enzymes and by levoglucosan dehydrogenase in vitro. The equilibrium direction in vivo depends on the NADP+/NADPH ratio and substrate concentrations.
Enzyme families and structural diversity
In simple terms: Different proteins can perform the same reaction, which matters for annotation and drug targeting.
The activity is not confined to a single protein family. A hepatic reductase specific for 1,5-anhydro-D-fructose was biochemically characterized in mammals, while dimeric dihydrodiol dehydrogenase was identified as an efficient primate 1,5-anhydro-D-fructose reductase. In bacteria, levoglucosan dehydrogenase catalyzes a related oxidation of an anhydro sugar, and its crystal structure has been determined. This diversity means that GO:0050571 can be assigned to multiple gene products, and functional studies must specify which enzyme is responsible in a given tissue or organism.
Physiological context and metabolite balance
In simple terms: The enzyme helps set the levels of two important sugar derivatives in the body.
1,5-anhydro-D-glucitol is a stable circulating metabolite used as a glycemic marker, and its levels increase in germinating amaranth seeds and ripening banana, indicating dynamic regulation in plants. The reductase activity interconverts this metabolite with 1,5-anhydro-D-fructose, which has been shown to inhibit adipogenesis in 3T3-L1 adipocytes and to attenuate LPS-induced iNOS expression. Thus, the enzyme contributes to the balance between a biomarker and a bioactive metabolite.
Biocatalytic and synthetic relevance
In simple terms: The enzyme can be used in the lab to make or modify rare sugars.
Biocatalytic and chemical methods have been developed for the preparation and transformation of 1,5-anhydro-D-fructose, and enzymatic reduction is part of this toolkit. The availability of recombinant enzymes, including dimeric dihydrodiol dehydrogenase and bacterial levoglucosan dehydrogenase, supports synthetic applications and mechanistic studies.
Key Genes Involved in GO:0050571 1,5-anhydro-D-fructose reductase activity
The following genes and proteins have been experimentally linked to 1,5-anhydro-D-fructose reductase activity or to the metabolism of its substrates.
| Gene | Major Role | Research Relevance |
|---|---|---|
| AKR1C1 (dimeric dihydrodiol dehydrogenase) | Efficient primate 1,5-anhydro-D-fructose reductase | Model for aldo-keto reductase catalysis and substrate specificity |
| Hepatic AF reductase (unnamed) | NADPH-dependent reductase specific for 1,5-anhydro-D-fructose | Original biochemical characterization of the activity |
| Bacterial membrane oxidoreductase | Oxidation of 1,5-anhydro-D-glucitol to 1,5-anhydro-D-fructose | Bacterial anhydro-sugar metabolism |
| Levoglucosan dehydrogenase | Bacterial anhydro-sugar oxidoreductase | Structural and functional model for related enzymes |
| AKR superfamily members | NADPH-dependent oxidoreduction | Comparative enzymology and inhibitor design |
| GLUT transporters (contextual) | Uptake of 1,5-anhydro-D-glucitol | Metabolite transport and biomarker biology |
| Adipogenesis regulators (contextual) | Modulated by 1,5-anhydro-D-fructose | Metabolic disease models |
| iNOS (NOS2) (contextual) | Inflammatory nitric oxide synthase | Inflammation studies with 1,5-anhydro-D-fructose |
| Plant homologs (amaranth, banana) | Metabolism of 1,5-anhydroglucitol during germination/ripening | Plant physiology and sugar metabolism |
| NADPH-generating enzymes (contextual) | Supply reducing equivalents | Redox balance for reductase activity |
| Aldose reductase family members | Related sugar reductions | Specificity comparison |
| Dihydrodiol dehydrogenase isoforms | Multifunctional oxidoreduction | Isoform-specific functions |
| Bacterial sugar kinases (contextual) | Anhydro-sugar phosphorylation | Pathway context |
| Fructose-bisphosphate aldolase (contextual) | Glycolytic flux | Metabolic context |
| PPARγ (contextual) | Adipogenesis transcription factor | Adipocyte differentiation studies |
| NF-κB pathway components (contextual) | Inflammatory signaling | iNOS regulation |
| 1,5-anhydro-D-fructose hydrolase (contextual) | Anhydro-sugar cleavage | Substrate availability |
How Is 1,5-anhydro-D-fructose reductase activity Regulated?
The activity of 1,5-anhydro-D-fructose reductase is regulated at multiple levels. Substrate availability of 1,5-anhydro-D-fructose and 1,5-anhydro-D-glucitol depends on dietary intake, renal reabsorption, and tissue-specific metabolism, as indicated by changes in 1,5-anhydroglucitol levels during seed germination and fruit ripening. The NADP+/NADPH ratio directly influences the direction of the reaction, since NADPH is the electron donor for reduction. Expression of the responsible enzymes may vary by tissue; dimeric dihydrodiol dehydrogenase is broadly expressed in primates and can act as an efficient 1,5-anhydro-D-fructose reductase. Inflammatory stimuli such as LPS can modulate the biological effects of 1,5-anhydro-D-fructose on iNOS expression, suggesting that the pathway intersects with inflammatory signaling. Adipogenic stimuli also affect the response to 1,5-anhydro-D-fructose in 3T3-L1 cells, indicating metabolic regulation.
1,5-anhydro-D-fructose reductase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| AKR1C1 (dimeric dihydrodiol dehydrogenase) | Diabetes biomarker metabolism; drug metabolism | CRISPR knockout in HepG2 or primate cells |
| Hepatic AF reductase (unnamed) | Glycemic control; liver metabolism | Knockout in mouse liver cell lines |
| Levoglucosan dehydrogenase | Bacterial anhydro-sugar metabolism | Bacterial knockout and complementation |
| Adipogenesis regulators (contextual) | Obesity and metabolic syndrome | 3T3-L1 adipocyte differentiation with CRISPR KO |
| iNOS (NOS2) (contextual) | Inflammation and sepsis | Macrophage knockout and LPS stimulation |
Diabetes and glycemic control
1,5-anhydro-D-glucitol is a clinically used marker of short-term glycemic control, and its serum levels are influenced by the interconversion with 1,5-anhydro-D-fructose. The reductase activity (GO:0050571) therefore has potential relevance to diabetes monitoring and to understanding individual variation in this biomarker. Enzymes such as dimeric dihydrodiol dehydrogenase may contribute to the steady-state levels of 1,5-anhydro-D-glucitol in primates.
Metabolic and adipogenesis regulation
1,5-anhydro-D-fructose inhibits adipogenesis in 3T3-L1 adipocytes, suggesting that the reductase activity and its substrate/product balance may influence adipose tissue biology. This links GO:0050571 to obesity and metabolic syndrome research, although the precise causal role of the enzyme requires further study.
Inflammation and iNOS signaling
1,5-anhydro-D-fructose attenuates LPS-induced iNOS expression, indicating an anti-inflammatory effect. The reductase activity could modulate the availability of this bioactive metabolite, thereby influencing inflammatory pathways. This connection is relevant to sepsis, chronic inflammation, and macrophage biology.
Enzyme superfamily and drug metabolism
Dimeric dihydrodiol dehydrogenase, a member of the aldo-keto reductase superfamily, acts as an efficient 1,5-anhydro-D-fructose reductase. This superfamily is involved in drug metabolism and detoxification, so the activity may intersect with pharmacokinetics and xenobiotic responses.
From 1,5-anhydro-D-fructose reductase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of AF reductase alter 1,5-anhydro-D-glucitol levels? | CRISPR knockout of AKR1C1 in hepatic cell lines |
| Can a point mutation abolish catalytic activity? | Point mutation at the catalytic residue of dimeric dihydrodiol dehydrogenase |
| Does overexpression increase 1,5-anhydro-D-fructose reduction? | Knock-in of a tagged AF reductase under a strong promoter |
| Which tissues express the enzyme? | Tagged knock-in with fluorescent reporter |
| Does the enzyme affect adipogenesis? | CRISPR knockout in 3T3-L1 cells followed by differentiation |
| Does the enzyme modulate iNOS induction? | Knockout in macrophages with LPS stimulation |
How to Study the 1,5-anhydro-D-fructose reductase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| NADPH oxidation assay | Enzyme activity | Kinetic characterization of AF reductase |
| LC-MS/MS | 1,5-anhydro-D-glucitol and 1,5-anhydro-D-fructose levels | Metabolite quantification in cells and tissues |
| X-ray crystallography | Three-dimensional structure | Active-site analysis of related enzymes |
| Site-directed mutagenesis | Catalytic residue function | Mechanistic studies |
| Western blot | Protein expression | Tissue distribution |
| qRT-PCR | mRNA levels | Expression profiling |
| Adipogenesis assay | Lipid accumulation | Metabolic function |
| iNOS reporter assay | Inflammatory signaling | Anti-inflammatory effects |
Enzymatic assays
Direct measurement of 1,5-anhydro-D-fructose reductase activity can be performed by monitoring NADPH oxidation at 340 nm using purified enzyme or cell lysates, as described for the hepatic reductase and dimeric dihydrodiol dehydrogenase. Substrate specificity can be tested with 1,5-anhydro-D-fructose and related sugars.
Metabolite quantification
Levels of 1,5-anhydro-D-glucitol and 1,5-anhydro-D-fructose can be quantified by chromatographic methods, as demonstrated in studies of germinating seeds and ripening fruit. These measurements link enzyme activity to physiological states.
Structural biology
Crystal structure determination of bacterial levoglucosan dehydrogenase provides a template for modeling the active site of related anhydro-sugar oxidoreductases. Homology modeling and docking can guide mutagenesis of candidate AF reductases.
Cell-based functional assays
Adipogenesis assays in 3T3-L1 cells and iNOS expression assays in LPS-stimulated macrophages can be used to test the biological effects of modulating AF reductase activity.
How CRISPR Can Be Used to Study GO:0050571 1,5-anhydro-D-fructose reductase activity
Knockout
CRISPR knockout of candidate genes such as AKR1C1 can eliminate 1,5-anhydro-D-fructose reductase activity in cell lines, allowing direct testing of its role in metabolite balance and downstream phenotypes. Knockout in 3T3-L1 cells can reveal whether the enzyme is required for adipogenesis inhibition by 1,5-anhydro-D-fructose.
Point Mutation
Point mutations at catalytic residues of dimeric dihydrodiol dehydrogenase can dissociate its 1,5-anhydro-D-fructose reductase activity from other functions, providing mechanistic insight. Such models are useful for separating enzymatic activity from scaffolding roles.
Knock-in
Knock-in of tagged versions of the enzyme can enable localization and interaction studies. For example, a fluorescent tag on the hepatic AF reductase or dimeric dihydrodiol dehydrogenase can reveal tissue-specific expression and subcellular distribution.
Overexpression
Overexpression of candidate AF reductases in cell lines can increase the conversion of 1,5-anhydro-D-fructose to 1,5-anhydro-D-glucitol, providing a gain-of-function system to study metabolic and inflammatory effects.
How EDITGENE Supports 1,5-anhydro-D-fructose reductase activity Research
Researchers studying 1,5-anhydro-D-fructose reductase activity-related genes often need to determine whether a candidate gene is causally involved in metabolite balance, adipogenesis, or inflammation. EDITGENE provides CRISPR-based cell model services to enable such functional validation.
Contact EDITGENE today to design your custom CRISPR model for 1,5-anhydro-D-fructose reductase activity research.
Frequently Asked Questions About 1,5-anhydro-D-fructose reductase activity
What is 1,5-anhydro-D-fructose reductase activity?
It is an enzyme activity defined by GO:0050571 that catalyzes the NADPH-dependent reduction of 1,5-anhydro-D-fructose to 1,5-anhydro-D-glucitol, or the reverse oxidation.
What genes are involved in 1,5-anhydro-D-fructose reductase activity?
Dimeric dihydrodiol dehydrogenase (AKR1C1) is an efficient primate enzyme, and a hepatic NADPH-dependent reductase specific for 1,5-anhydro-D-fructose has been purified.
What is the reaction catalyzed by GO:0050571?
The reaction is 1,5-anhydro-D-glucitol + NADP+ = 1,5-anhydro-D-fructose + H+ + NADPH, as defined by QuickGO.
Which cofactor does 1,5-anhydro-D-fructose reductase use?
It uses NADPH as the electron donor for reduction and produces NADP+.
Is 1,5-anhydro-D-fructose reductase the same as dihydrodiol dehydrogenase?
Dimeric dihydrodiol dehydrogenase can act as an efficient 1,5-anhydro-D-fructose reductase in primates, but it is a multifunctional enzyme.
What is the role of 1,5-anhydro-D-fructose in adipogenesis?
1,5-anhydro-D-fructose inhibits adipogenesis in 3T3-L1 adipocytes, suggesting a role in fat cell differentiation.
Does 1,5-anhydro-D-fructose affect inflammation?
It attenuates LPS-induced iNOS expression, indicating anti-inflammatory activity.
How is 1,5-anhydro-D-glucitol used in diabetes?
1,5-anhydro-D-glucitol is a serum marker of short-term glycemic control, and its levels are influenced by interconversion with 1,5-anhydro-D-fructose.
Are there bacterial enzymes with similar activity?
Yes, bacterial membrane enzymes oxidize 1,5-anhydro-D-glucitol to 1,5-anhydro-D-fructose, and levoglucosan dehydrogenase acts on related anhydro sugars.
How can I study 1,5-anhydro-D-fructose reductase activity in the lab?
Enzymatic NADPH oxidation assays, metabolite quantification, and CRISPR knockout or overexpression models are commonly used.
Conclusion
GO:0050571 (1,5-anhydro-D-fructose reductase activity) represents a specific but biologically significant redox reaction linking anhydro sugar metabolism to glycemic control, adipogenesis, and inflammation. The enzyme was first characterized as a hepatic NADPH-dependent reductase and later shown to be catalyzed efficiently by dimeric dihydrodiol dehydrogenase in primates. Bacterial homologs provide structural and evolutionary context. For researchers, precise annotation and functional validation using CRISPR models will clarify the physiological and pathological roles of this activity. EDITGENE offers comprehensive CRISPR services to support such studies.
References
- 1. Hara A et al.. 2020. Dimeric dihydrodiol dehydrogenase is an efficient primate 1,5-anhydro-D-fructose reductase.. Biochem Biophys Res Commun 526(3):728-732 PMID: 32253031
- 2. Lundt I et al.. 2010. 1,5-Anhydro-D-fructose: biocatalytic and chemical synthetic methods for the preparation, transformation and derivatization.. Carbohydr Res 345(2):181-90 PMID: 20004890
- 3. Kojima-Yuasa A et al.. 2012. Effect of 1,5-anhydro-D-fructose on the inhibition of adipogenesis in 3T3-L1 adipocytes.. Nat Prod Commun 7(11):1501-6 PMID: 23285817
- 4. Sakuma M et al.. 1998. Purification and some properties of a hepatic NADPH-dependent reductase that specifically acts on 1,5-anhydro-D-fructose.. J Biochem 123(1):189-93 PMID: 9504428
- 5. Meng X et al.. 2009. Attenuation of LPS-induced iNOS expression by 1,5-anhydro-d-fructose.. Biochem Biophys Res Commun 387(1):42-6 PMID: 19559007
- 6. Nakamura T et al.. 1986. Oxidation of 1,5-anhydro-D-glucitol to 1,5-anhydro-D-fructose catalyzed by an enzyme from bacterial membranes.. J Biochem 99(3):607-13 PMID: 3711037
- 7. Sugiura M et al.. 2018. Identification, functional characterization, and crystal structure determination of bacterial levoglucosan dehydrogenase.. J Biol Chem 293(45):17375-17386 PMID: 30224354
- 8. Konishi Y et al.. 2000. Increases in 1,5-anhydroglucitol levels in germinating amaranth seeds and in ripening banana.. Biosci Biotechnol Biochem 64(11):2462-5 PMID: 11193417
