GO:0035798 2-alkenal reductase (NADPH) activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0035798 defines 2-alkenal reductase (NADPH) activity, which catalyzes the NADPH-dependent reduction of the carbon-carbon double bond of reactive 2-alkenals to less toxic n-alkanals.
• This activity is a key enzymatic detoxification route for lipid peroxide-derived reactive carbonyls, protecting cells from oxidative and photooxidative injury.
• In plants, 2-alkenal reductase (AER) enzymes such as the Arabidopsis P1-zeta-crystallin and tobacco AER detoxify reactive aldehydes produced under stress.
• Up-regulation of 2-alkenal reductase improves low-nitrogen tolerance in maize by alleviating oxidative stress.
• The rice OsAER1 gene shows root-specific expression driven by a defined promoter region, linking this activity to root physiology.
• In mammals, LTB4 12-hydroxydehydrogenase/15-ketoprostaglandin Delta 13-reductase (LTB4 12-HD/PGR) reduces the alpha,beta-unsaturated ketone of the NSAID CS-670, showing that this activity also participates in drug metabolism.
Description
2-alkenal reductase (NADPH) activity (GO:0035798) is a molecular function that catalyzes the NADPH-dependent reduction of the carbon-carbon double bond of 2-alkenals, converting them to n-alkanals. This reaction is chemically defined as n-alkanal + NADP+ = alk-2-enal + NADPH + H+, and the enzyme is also known as NADPH:2-alkenal alpha,beta-hydrogenase. The activity is best understood as a detoxification mechanism: 2-alkenals are reactive carbonyls generated by lipid peroxidation under oxidative stress, and their removal protects cellular macromolecules from damage. In plants, this function has been studied in Arabidopsis, tobacco, maize, and rice, where it contributes to stress tolerance and root-specific physiology. In mammals, a related enzyme, LTB4 12-hydroxydehydrogenase/15-ketoprostaglandin Delta 13-reductase, catalyzes the reduction of an alpha,beta-unsaturated ketone in the NSAID CS-670, indicating that this activity also plays a role in xenobiotic metabolism. Because reactive aldehydes are implicated in oxidative stress-related damage, understanding GO:0035798 is relevant to plant stress biology, human drug metabolism, and cellular protection mechanisms.
2-alkenal reductase (NADPH) activity At A Glance
| GO ID | GO:0035798 |
|---|---|
| GO term | 2-alkenal reductase (NADPH) activity |
| Ontology | molecular_function |
| Synonym | NADPH:2-alkenal alpha,beta-hydrogenase activity |
| Definition | Catalysis of the reaction: n-alkanal + NADP+ = alk-2-enal + NADPH + H+. |
| Major function | NADPH-dependent reduction of the carbon-carbon double bond of reactive 2-alkenals to less toxic n-alkanals. |
| Cofactor | NADPH serves as the electron donor, being oxidized to NADP+. |
| Substrate class | 2-alkenals, including lipid peroxide-derived reactive carbonyls. |
| Representative enzymes | Arabidopsis P1-zeta-crystallin, tobacco 2-alkenal reductase, maize 2-alkenal reductase, rice OsAER1, mammalian LTB4 12-HD/PGR. |
| Biological context | Detoxification of reactive aldehydes under oxidative stress; low-nitrogen tolerance in maize; root-specific expression in rice; NSAID metabolism in mammals. |
What Is GO:0035798?
2-alkenal reductase (NADPH) activity is defined by the Gene Ontology as the catalysis of the reaction n-alkanal + NADP+ = alk-2-enal + NADPH + H+. In other words, the enzyme transfers a hydride from NADPH to the beta-carbon of an alpha,beta-unsaturated aldehyde (2-alkenal), reducing the double bond and producing a saturated aldehyde (n-alkanal) while oxidizing NADPH to NADP+. This activity is synonymous with NADPH:2-alkenal alpha,beta-hydrogenase activity. It belongs to the molecular_function aspect of the Gene Ontology and is distinct from aldehyde reductases that reduce the carbonyl group rather than the double bond.
Why Is 2-alkenal reductase (NADPH) activity Important in Cell Biology?
GO:0035798 is important because it provides a direct enzymatic defense against reactive carbonyls that arise from lipid peroxidation, a process that damages proteins, nucleic acids, and membranes under oxidative stress. In crops, up-regulation of 2-alkenal reductase improves low-nitrogen tolerance by alleviating oxidative stress, linking this activity to agricultural resilience. In rice, the root-specific expression of OsAER1 suggests a specialized role in root physiology and stress responses. In mammals, the same activity is associated with the metabolism of an aryl propionic acid NSAID, indicating relevance to drug disposition and potentially to inflammatory mediator turnover. Thus, GO:0035798 bridges plant stress biology, redox homeostasis, and xenobiotic metabolism, making it a valuable target for both basic and applied research.
• Protects against photooxidative injury in plants by detoxifying lipid peroxide-derived reactive carbonyls.
• Improves low-nitrogen tolerance in maize through alleviation of oxidative stress.
• Shows root-specific expression in rice, linking the activity to root development and stress adaptation.
• Contributes to the detoxification of reactive aldehydes that would otherwise modify proteins and DNA.
• Participates in the metabolism of an aryl propionic acid NSAID in mammals, indicating a role in drug metabolism.
• Represents a conserved enzymatic strategy for managing oxidative stress across plants and mammals.
• Provides a potential target for engineering stress-tolerant crops through overexpression.
• Helps maintain cellular redox balance by consuming NADPH and removing electrophilic aldehydes.
• Is relevant to understanding inflammatory mediator turnover via LTB4 12-HD/PGR activity.
• Offers a biochemical marker for oxidative stress responses in plant and animal systems.
What Happens During 2-alkenal reductase (NADPH) activity?
Substrate recognition and binding
In simple terms: The enzyme first grabs the harmful aldehyde and the NADPH helper molecule.
The reaction begins when the enzyme binds a 2-alkenal substrate, an alpha,beta-unsaturated aldehyde often derived from lipid peroxidation, together with the reduced cofactor NADPH. In Arabidopsis, the P1-zeta-crystallin enzyme catalyzes the alpha,beta-hydrogenation of 2-alkenals, demonstrating specificity for the double bond rather than the carbonyl group. This binding step positions the substrate for hydride transfer and is essential for detoxication of reactive aldehydes.
Hydride transfer from NADPH
In simple terms: NADPH donates a hydride to the aldehyde, breaking the double bond.
Once bound, NADPH transfers a hydride to the beta-carbon of the 2-alkenal, reducing the carbon-carbon double bond and yielding a saturated n-alkanal while NADPH is oxidized to NADP+. This step is the chemical heart of GO:0035798 and is described by the reaction n-alkanal + NADP+ = alk-2-enal + NADPH + H+. The reaction is stereospecific and produces the less reactive aldehyde, thereby diminishing the electrophilic threat to cellular components.
Product release and detoxification
In simple terms: The now safer aldehyde is released, and the cell is protected.
After reduction, the n-alkanal product is released, and the enzyme is ready for another catalytic cycle. The conversion of reactive 2-alkenals to less toxic n-alkanals is a detoxification event that protects against photooxidative injury in tobacco leaves and against oxidative stress in maize. This product release step completes the catalytic cycle and contributes to cellular redox homeostasis.
Physiological context in plants
In simple terms: In plants, this activity helps them survive stress like too much light or too little nitrogen.
In tobacco, 2-alkenal reductase protects leaves against photooxidative injury by detoxifying lipid peroxide-derived reactive carbonyls. In maize, up-regulated 2-alkenal reductase expression improves low-nitrogen tolerance by alleviating oxidative stress. In rice, the OsAER1 gene shows root-specific expression, suggesting a specialized role in root physiology. These findings illustrate how GO:0035798 operates in diverse plant stress contexts.
Mammalian and pharmacological relevance
In simple terms: In mammals, a similar enzyme helps process certain drugs.
In mammals, LTB4 12-hydroxydehydrogenase/15-ketoprostaglandin Delta 13-reductase (LTB4 12-HD/PGR) is responsible for the reduction of a double bond of the alpha,beta-unsaturated ketone of the aryl propionic acid NSAID CS-670. This demonstrates that the alpha,beta-hydrogenation activity described by GO:0035798 extends beyond plant aldehyde detoxification to xenobiotic metabolism. The enzyme thus participates in both endogenous and exogenous substrate processing.
Key Genes Involved in GO:0035798 2-alkenal reductase (NADPH) activity
The following genes and proteins are experimentally linked to 2-alkenal reductase (NADPH) activity or its physiological roles.
| Gene | Major Role | Research Relevance |
|---|---|---|
| AER (tobacco) | 2-alkenal reductase that detoxifies lipid peroxide-derived reactive carbonyls | Protects against photooxidative injury in tobacco leaves |
| P1-zeta-crystallin (Arabidopsis) | Catalyzes alpha,beta-hydrogenation of 2-alkenals | Detoxication of lipid peroxide-derived reactive aldehydes |
| ZmAER (maize) | Up-regulated 2-alkenal reductase improves low-nitrogen tolerance | Alleviates oxidative stress under low nitrogen |
| OsAER1 (rice) | Root-specific expression of alkenal reductase | Promoter deletion analysis reveals root-specific expression |
| LTB4 12-HD/PGR (mammalian) | Reduces double bond of alpha,beta-unsaturated ketone of NSAID CS-670 | Drug metabolism and inflammatory mediator turnover |
| NADPH (cofactor) | Provides reducing equivalents for the reaction | Essential for catalytic activity |
| 2-alkenal (substrate) | Reactive aldehyde substrate derived from lipid peroxidation | Central to detoxification assays |
| n-alkanal (product) | Less toxic saturated aldehyde product | Marker of enzyme activity |
| Reactive carbonyls | Toxic electrophiles generated under oxidative stress | Targets for detoxification |
| Lipid peroxides | Source of 2-alkenals | Upstream of enzyme action |
| NADP+ | Oxidized cofactor product | Indicates turnover |
| H+ | Proton released in the reaction | Part of the reaction equation |
| CS-670 (NSAID) | Aryl propionic acid drug metabolized by LTB4 12-HD/PGR | Substrate for mammalian enzyme |
| 15-ketoprostaglandin Delta 13-reductase | Enzymatic activity of LTB4 12-HD/PGR | Linked to prostaglandin metabolism |
| Leukotriene B4 12-hydroxydehydrogenase | Enzymatic activity of LTB4 12-HD/PGR | Linked to leukotriene metabolism |
| Zeta-crystallin | Lens protein with 2-alkenal reductase activity in Arabidopsis | Model for dual-function proteins |
| Quinone oxidoreductase | Related activity of P1-zeta-crystallin | Broad substrate specificity |
| Aldehyde detoxification enzymes | General class including 2-alkenal reductases | Comparative studies |
How Is 2-alkenal reductase (NADPH) activity Regulated?
The expression and activity of 2-alkenal reductase are regulated in response to environmental and physiological cues. In maize, up-regulation of 2-alkenal reductase expression improves low-nitrogen tolerance by alleviating oxidative stress, indicating that the gene is responsive to nitrogen availability. In rice, promoter deletion analysis revealed root-specific expression of the OsAER1 gene, suggesting tissue-specific transcriptional regulation. In tobacco, the enzyme protects against photooxidative injury, implying that its activity may be modulated by light and oxidative conditions. These examples show that regulation occurs at the transcriptional level and in response to stress, but the precise signaling pathways remain to be fully defined.
2-alkenal reductase (NADPH) activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| Zm AER | Low-nitrogen tolerance and oxidative stress in maize | Overexpression in maize or Arabidopsis |
| Tobacco AER | Photooxidative injury | Knockout or overexpression in tobacco leaves |
| OsAER1 | Root-specific stress responses in rice | Promoter deletion or root-specific knockout |
| P1-zeta-crystallin | Aldehyde detoxification and oxidative stress | Arabidopsis knockout and point mutation |
| LTB4 12-HD/PGR | NSAID metabolism and inflammatory mediator turnover | Mammalian cell lines with knockout or knockdown |
Oxidative stress and inflammatory conditions
Reactive aldehydes produced by lipid peroxidation contribute to oxidative stress and inflammation. The 2-alkenal reductase activity detoxifies these compounds, and in mammals, LTB4 12-HD/PGR reduces an alpha,beta-unsaturated ketone of the NSAID CS-670, linking the activity to inflammatory mediator and drug metabolism. In plants, the enzyme protects against photooxidative injury, demonstrating a conserved role in mitigating oxidative damage.
Crop stress tolerance and agricultural disease
In maize, up-regulated 2-alkenal reductase improves low-nitrogen tolerance by alleviating oxidative stress, which is relevant to crop health and yield under adverse conditions. In rice, root-specific expression of OsAER1 suggests a role in root physiology that may influence stress adaptation. These findings connect GO:0035798 to plant disease resistance and abiotic stress resilience.
Drug metabolism and pharmacological outcomes
The mammalian enzyme LTB4 12-HD/PGR is responsible for the reduction of a double bond of the alpha,beta-unsaturated ketone of the aryl propionic acid NSAID CS-670, indicating that this activity can influence drug disposition and potentially drug efficacy or toxicity. This has implications for understanding inter-individual variability in NSAID metabolism.
From 2-alkenal reductase (NADPH) activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of 2-alkenal reductase increase sensitivity to oxidative stress? | Knockout cell lines or plants |
| Does a specific catalytic residue mediate hydride transfer? | Point mutation of predicted active-site residues |
| Can tagged enzyme be used to track localization? | Knock-in of epitope tag |
| Does overexpression improve stress tolerance? | Overexpression in maize or tobacco |
| Is root-specific expression controlled by a defined promoter region? | Promoter deletion analysis in rice |
| Does the mammalian enzyme metabolize NSAIDs? | Knockout or knockdown in mammalian cells |
How to Study the 2-alkenal reductase (NADPH) activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| NADPH oxidation assay | Enzyme activity via decrease in absorbance at 340 nm | Characterizing 2-alkenal reductase kinetics |
| RT-qPCR | mRNA expression levels | Stress-induced up-regulation in maize |
| RNA-seq | Global transcriptome changes | Identifying co-expressed genes under stress |
| Promoter deletion analysis | Regulatory regions controlling expression | Root-specific expression of OsAER1 |
| Lipid peroxidation assay | Oxidative damage markers | Photooxidative injury in tobacco |
| Reactive carbonyl measurement | Levels of toxic aldehydes | Detoxification capacity |
| HPLC or LC-MS | Metabolite identification and quantification | NSAID metabolism by LTB4 12-HD/PGR |
| Western blot | Protein abundance | Overexpression or knockout validation |
Enzyme activity assays
Direct measurement of 2-alkenal reductase activity uses NADPH oxidation monitored spectrophotometrically at 340 nm in the presence of a 2-alkenal substrate. This method was used to characterize the Arabidopsis P1-zeta-crystallin enzyme and to confirm alpha,beta-hydrogenation of 2-alkenals. Such assays are essential for validating GO:0035798 in candidate enzymes.
Gene expression analysis
Transcript levels of genes encoding 2-alkenal reductases can be quantified by RT-qPCR or RNA-seq. In maize, up-regulation of 2-alkenal reductase expression under low nitrogen was demonstrated, linking expression to stress tolerance. In rice, promoter deletion analysis revealed root-specific expression of OsAER1, which can be further studied by reporter assays.
Stress phenotyping
Physiological and biochemical phenotyping under oxidative stress conditions, such as photooxidative treatment in tobacco or low-nitrogen growth in maize, can reveal the protective role of 2-alkenal reductase. These experiments measure parameters like chlorophyll content, lipid peroxidation, and reactive carbonyl levels.
Drug metabolism studies
In mammalian systems, the metabolism of NSAIDs such as CS-670 can be studied using liver fractions or recombinant enzymes to assess the role of LTB4 12-HD/PGR in double-bond reduction. Such studies connect GO:0035798 to pharmacological outcomes.
How CRISPR Can Be Used to Study GO:0035798 2-alkenal reductase (NADPH) activity
Knockout
CRISPR knockout of genes encoding 2-alkenal reductase can reveal loss-of-function phenotypes under oxidative stress. For example, knocking out the tobacco AER gene would test its role in protecting leaves from photooxidative injury. Similarly, knockout of OsAER1 in rice could clarify its root-specific function.
Point Mutation
Point mutations can be introduced into catalytic residues of 2-alkenal reductase to dissect the hydride transfer mechanism. For instance, mutating residues in the active site of Arabidopsis P1-zeta-crystallin could abolish alpha,beta-hydrogenation activity while retaining protein stability. Such mutants help confirm the enzymatic basis of GO:0035798.
Knock-in
Knock-in of epitope tags or fluorescent proteins at the endogenous locus allows tracking of 2-alkenal reductase localization and dynamics. Tagging the tobacco AER or rice OsAER1 would enable imaging studies in planta. This approach preserves native regulatory elements.
Overexpression
Overexpression of 2-alkenal reductase genes can enhance stress tolerance. In maize, up-regulation of 2-alkenal reductase improved low-nitrogen tolerance by alleviating oxidative stress. Overexpression in tobacco also protected against photooxidative injury. These gain-of-function models are valuable for crop improvement.
How EDITGENE Supports 2-alkenal reductase (NADPH) activity Research
Researchers studying 2-alkenal reductase (NADPH) activity-related genes often need to determine whether a candidate gene is causally involved in detoxification, stress tolerance, or drug metabolism. Establishing causality requires precise genetic models that can knockout, mutate, tag, or overexpress the gene of interest in relevant cell or organism systems. EDITGENE provides a suite of CRISPR-based services to generate such models efficiently and reproducibly.
Contact EDITGENE today to design your custom CRISPR model for 2-alkenal reductase (NADPH) activity research.
Frequently Asked Questions About 2-alkenal reductase (NADPH) activity
What is 2-alkenal reductase (NADPH) activity?
It is a molecular function defined by GO:0035798 that catalyzes the NADPH-dependent reduction of the carbon-carbon double bond of 2-alkenals to n-alkanals, detoxifying reactive aldehydes.
What genes are involved in 2-alkenal reductase (NADPH) activity?
Genes include tobacco AER, Arabidopsis P1-zeta-crystallin, maize 2-alkenal reductase, rice OsAER1, and mammalian LTB4 12-HD/PGR.
What is the reaction catalyzed by 2-alkenal reductase?
The reaction is n-alkanal + NADP+ = alk-2-enal + NADPH + H+, where NADPH reduces the double bond of a 2-alkenal.
Why is 2-alkenal reductase important in plants?
It protects against photooxidative injury in tobacco and improves low-nitrogen tolerance in maize by detoxifying reactive carbonyls.
Is 2-alkenal reductase involved in human drug metabolism?
Yes, the mammalian enzyme LTB4 12-HD/PGR reduces the alpha,beta-unsaturated ketone of the NSAID CS-670.
What is the synonym for GO:0035798?
The synonym is NADPH:2-alkenal alpha,beta-hydrogenase activity.
How can I study 2-alkenal reductase activity in the lab?
You can use NADPH oxidation assays, gene expression analysis, stress phenotyping, and drug metabolism studies.
What model organisms are used for 2-alkenal reductase research?
Arabidopsis, tobacco, maize, rice, and mammalian cell lines have been used.
Does 2-alkenal reductase protect against oxidative stress?
Yes, it detoxifies lipid peroxide-derived reactive carbonyls, thereby alleviating oxidative stress.
How does CRISPR help study 2-alkenal reductase?
CRISPR enables knockout, point mutation, knock-in, and overexpression models to test gene function and causality.
Conclusion
GO:0035798, 2-alkenal reductase (NADPH) activity, represents a conserved enzymatic mechanism for detoxifying reactive aldehydes generated by lipid peroxidation. Its roles span plant stress tolerance, root-specific physiology, and mammalian drug metabolism, as demonstrated by studies in tobacco, Arabidopsis, maize, rice, and mammalian systems. Understanding this activity provides insights into oxidative stress defense and offers opportunities for crop improvement and pharmacological research. CRISPR-based models from EDITGENE can accelerate functional validation of genes encoding this activity.
References
- 1. Wang Y et al.. 2021. Up-regulated 2-alkenal reductase expression improves low-nitrogen tolerance in maize by alleviating oxidative stress.. Plant Cell Environ 44(2):559-573 PMID: 33215716
- 2. Mano J et al.. 2005. Protection against photooxidative injury of tobacco leaves by 2-alkenal reductase. Detoxication of lipid peroxide-derived reactive carbonyls.. Plant Physiol 139(4):1773-83 PMID: 16299173
- 3. Apriana A et al.. 2019. Promoter deletion analysis reveals root-specific expression of the alkenal reductase gene (OsAER1) in Oryza sativa.. Funct Plant Biol 46(4):376-391 PMID: 32172746
- 4. Mano J et al.. 2002. The NADPH:quinone oxidoreductase P1-zeta-crystallin in Arabidopsis catalyzes the alpha,beta-hydrogenation of 2-alkenals: detoxication of the lipid peroxide-derived reactive aldehydes.. Plant Cell Physiol 43(12):1445-55 PMID: 12514241
- 5. Itoh K et al.. 2008. Leukotriene B4 12-hydroxydehydrogenase/15-ketoprostaglandin Delta 13-reductase (LTB4 12-HD/PGR) responsible for the reduction of a double-bond of the alpha,beta-unsaturated ketone of an aryl propionic acid non-steroidal anti-inflammatory agent CS-670.. Xenobiotica 38(3):249-63 PMID: 18274955
