GO:0004301 epoxide hydrolase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004301 epoxide hydrolase activity describes the catalysis of an epoxide plus water to an ethanediol (vicinal diol), a fundamental detoxification and lipid-signaling reaction.
• Soluble epoxide hydrolase (sEH, gene EPHX2) is the most studied enzyme carrying this activity and hydrolyzes epoxy-fatty acids such as EETs to their corresponding diols.
• Beyond its canonical hydrolase function, sEH can also exhibit phosphatase activity, expanding its regulatory roles in cell signaling.
• Natural products and synthetic inhibitors of epoxide hydrolase activity are actively pursued for anti-inflammatory and neuroprotective applications.
• Directed evolution and immobilization strategies have been used to enhance the catalytic efficiency and enantioselectivity of epoxide hydrolases for biotechnological use.
• Epoxide hydrolase activity is measurable in human lymphocytes and other tissues, making it a accessible biomarker for gene-environment studies.
Description
Epoxide hydrolase activity (GO:0004301) is a molecular function that catalyzes the addition of water to an epoxide, yielding a vicinal diol (ethanediol). This reaction is central to the detoxification of reactive epoxides and the metabolic conversion of signaling lipids. The term encompasses multiple enzymes, including microsomal and soluble epoxide hydrolases, which differ in substrate specificity, tissue distribution, and subcellular localization. In biomedical research, epoxide hydrolase activity is studied for its roles in xenobiotic metabolism, inflammation resolution, and vascular tone regulation. The soluble epoxide hydrolase (sEH), encoded by EPHX2, is a prominent example that hydrolyzes epoxy-eicosatrienoic acids (EETs) to dihydroxyeicosatrienoic acids (DHETs), thereby modulating cardiovascular and renal functions. Recent studies have also uncovered non-canonical phosphatase activity for sEH, suggesting broader signaling roles. Given its impact on drug metabolism and disease, epoxide hydrolase activity remains a target for inhibitor development and enzyme engineering.
epoxide hydrolase activity At A Glance
| GO ID | GO:0004301 |
|---|---|
| GO term | epoxide hydrolase activity |
| Ontology | molecular_function |
| Synonym | arene-oxide hydratase activity; aryl epoxide hydrase activity; cytosolic epoxide hydrolase activity; epoxide hydrase activity; epoxide hydratase activity; sEH; soluble epoxide hydrolase activity; trans-stilbene oxide hydrolase activity |
| Definition | Catalysis of the reaction: an epoxide + H2O = an ethanediol. |
| Major function | Hydrolysis of epoxide rings to diols, involved in detoxification and lipid signaling. |
| Representative enzymes | Soluble epoxide hydrolase (EPHX2), microsomal epoxide hydrolase (EPHX1), and other epoxide hydrolases. |
| Substrates | Epoxides including xenobiotic epoxides, epoxy-fatty acids (e.g., EETs), and trans-stilbene oxide. |
| Inhibitors | Natural products (e.g., from Glycyrrhiza uralensis, Aloe) and synthetic sEH inhibitors. |
What Is GO:0004301?
According to the Gene Ontology, GO:0004301 epoxide hydrolase activity is defined as the catalysis of the reaction: an epoxide + H2O = an ethanediol. In other words, it is the enzymatic hydrolysis of an epoxide ring to form a diol. This activity is also known by synonyms such as arene-oxide hydratase activity, aryl epoxide hydrase activity, cytosolic epoxide hydrolase activity, epoxide hydrase activity, epoxide hydratase activity, sEH, soluble epoxide hydrolase activity, and trans-stilbene oxide hydrolase activity. The reaction typically involves the nucleophilic attack of water on an epoxide substrate, leading to ring opening and formation of a vicinal diol.
Why Is epoxide hydrolase activity Important in Cell Biology?
Epoxide hydrolase activity is critically important because it controls the levels of reactive epoxides and signaling lipids that influence inflammation, blood pressure, pain perception, and drug metabolism. Dysregulation of this activity has been linked to cardiovascular diseases, renal dysfunction, and neuroinflammation. Moreover, epoxide hydrolases are promising biocatalysts for the enantioselective synthesis of chiral diols in pharmaceutical manufacturing.
• Detoxifies carcinogenic and reactive epoxides derived from environmental chemicals and drugs.
• Regulates levels of epoxy-fatty acids (EETs) that have vasodilatory and anti-inflammatory effects.
• Soluble epoxide hydrolase inhibitors are investigated for treating hypertension, pain, and inflammatory diseases.
• Plays a role in neuroinflammation and neurodegeneration, with sEH inhibition showing neuroprotective effects.
• Epoxide hydrolase activity in lymphocytes can serve as a biomarker for individual susceptibility to genotoxic agents.
• Enzyme engineering of epoxide hydrolases enables green chemistry for producing enantiopure diols.
• Natural product inhibitors from medicinal plants provide scaffolds for drug development.
• The phosphatase activity of sEH reveals crosstalk between lipid signaling and phosphorylation pathways.
What Happens During epoxide hydrolase activity?
Substrate binding and orientation
In simple terms: The enzyme grabs an epoxide molecule and positions it for reaction.
Epoxide hydrolases bind their substrates through a hydrophobic tunnel that accommodates the epoxide ring. For soluble epoxide hydrolase, the active site contains a catalytic triad (Asp, His, Asp/Glu) that polarizes a water molecule. Substrate specificity varies: microsomal epoxide hydrolase prefers small xenobiotic epoxides, while soluble epoxide hydrolase favors lipid epoxides such as EETs. Structural studies have revealed that the enzyme undergoes conformational changes upon substrate binding to stabilize the transition state.
Catalytic hydrolysis
In simple terms: Water attacks the epoxide, breaking the ring and forming a diol.
The catalytic mechanism involves nucleophilic attack of an activated water molecule on one of the epoxide carbons, leading to ring opening and formation of a vicinal diol. This reaction is stereospecific, often yielding enantiopure products. For example, hydrolysis of styrene oxide by epoxide hydrolase produces 1-phenyl-1,2-ethanediol with high enantioselectivity. The reaction proceeds without the need for cofactors such as NAD+ or FAD, relying solely on the catalytic residues and water.
Product release and enzyme turnover
In simple terms: The diol product leaves, and the enzyme is ready for another round.
After hydrolysis, the diol product is released from the active site, and the enzyme returns to its resting state. Product release can be rate-limiting for some epoxide hydrolases, and engineering efforts have aimed to improve turnover rates. The released diols can be further metabolized or excreted, contributing to detoxification.
Regulation by inhibitors and cellular environment
In simple terms: Other molecules can block the enzyme, and cellular conditions affect its speed.
Epoxide hydrolase activity is modulated by endogenous and exogenous inhibitors. Natural compounds from Glycyrrhiza uralensis and Aloe have been shown to inhibit soluble epoxide hydrolase. Additionally, the enzyme's activity can be influenced by post-translational modifications and cellular redox state, although these mechanisms are less defined. The phosphatase activity of sEH suggests that it may integrate lipid and phosphate signaling under certain conditions.
Key Genes Involved in GO:0004301 epoxide hydrolase activity
The following genes encode proteins that exhibit epoxide hydrolase activity or are directly involved in its regulation and study.
| Gene | Major Role | Research Relevance |
|---|---|---|
| EPHX2 | Soluble epoxide hydrolase; hydrolyzes EETs to DHETs | Target for cardiovascular and inflammatory disease; inhibitor development |
| EPHX1 | Microsomal epoxide hydrolase; detoxifies xenobiotic epoxides | Role in drug metabolism and cancer susceptibility |
| EPHX3 | Epoxide hydrolase 3; hydrolyzes epoxides | Less characterized; potential role in lipid metabolism |
| EPHX4 | Epoxide hydrolase 4; hydrolyzes epoxides | Emerging role in cellular stress responses |
| CYP2C8 | Cytochrome P450; produces EETs from arachidonic acid | Upstream of sEH in EET signaling |
| CYP2J2 | Cytochrome P450; produces EETs | Modulates sEH substrate availability |
| PTGS2 | Cyclooxygenase-2; involved in inflammation | Crosstalk with epoxide hydrolase pathways |
| ALOX5 | Lipoxygenase; produces leukotrienes | Interplay with epoxide hydrolase in inflammation |
| NFE2L2 | Transcription factor; regulates antioxidant response | May influence epoxide hydrolase expression |
| PPARA | Peroxisome proliferator-activated receptor alpha | Regulates lipid metabolism genes including EPHX2 |
| PPARG | Peroxisome proliferator-activated receptor gamma | Linked to sEH inhibition effects |
| MAPK1 | Mitogen-activated protein kinase 1 | Signaling downstream of epoxide hydrolase activity |
| MAPK3 | Mitogen-activated protein kinase 3 | Involved in neuroinflammation pathways |
| PBK | PDZ-binding kinase; target of britannilactone | Neuroinflammation; potential crosstalk with sEH |
| TNF | Tumor necrosis factor | Inflammatory cytokine modulated by sEH inhibitors |
| IL6 | Interleukin-6 | Inflammatory marker affected by epoxide hydrolase activity |
| VCAM1 | Vascular cell adhesion molecule 1 | Endothelial inflammation marker |
How Is epoxide hydrolase activity Regulated?
Epoxide hydrolase activity is regulated at multiple levels. Transcriptional regulation of EPHX2 and EPHX1 can be influenced by nuclear receptors such as PPARA and NFE2L2. Post-translational modifications, including phosphorylation, may affect sEH stability and subcellular localization. Additionally, the enzyme's activity is subject to inhibition by endogenous lipids and exogenous compounds, as demonstrated by natural product inhibitors. The phosphatase activity of sEH suggests that it may be regulated by phosphate availability and signaling cascades.
epoxide hydrolase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| EPHX2 | Hypertension, inflammation, neuroinflammation | EPHX2 knockout mice; sEH inhibitor treatment |
| EPHX1 | Cancer susceptibility, drug metabolism | EPHX1 knockout cell lines; genotoxicity assays |
| EPHX2 | Renal injury | Ischemia-reperfusion models in EPHX2-/- mice |
| EPHX2 | Pain | Inflammatory pain models with sEH inhibitors |
| PBK | Neuroinflammation | PBK knockout or inhibitor-treated microglia |
Cardiovascular and renal diseases
Soluble epoxide hydrolase (sEH) hydrolyzes EETs, which are vasodilatory and anti-inflammatory, to less active DHETs. Inhibition of sEH activity increases EET levels, lowering blood pressure and reducing renal injury in animal models. Thus, epoxide hydrolase activity is a therapeutic target for hypertension and kidney disease.
Inflammation and pain
Epoxide hydrolase activity modulates inflammatory mediators. Inhibitors of sEH reduce inflammatory pain and edema in preclinical models. Natural products from Glycyrrhiza uralensis and Aloe have shown sEH inhibitory activity, supporting their traditional use for inflammatory conditions.
Neuroinflammation and neurodegeneration
In neuroinflammatory conditions, sEH inhibition has been shown to reduce microglial activation and neuronal damage. A recent study identified a small molecule, 1-O-acetyl-4R,6S-britannilactone, that targets PBK and modulates neuroinflammation, potentially through epoxide hydrolase-related pathways. This highlights the role of epoxide hydrolase activity in brain health.
Cancer and xenobiotic metabolism
Microsomal epoxide hydrolase (EPHX1) detoxifies carcinogenic epoxides, and polymorphisms in EPHX1 have been associated with altered cancer risk. Additionally, epoxide hydrolase activity in lymphocytes may serve as a biomarker for individual susceptibility to genotoxic agents.
From epoxide hydrolase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of EPHX2 affect blood pressure? | EPHX2 knockout mouse |
| Can a point mutation in EPHX2 alter substrate specificity? | Knock-in mouse expressing mutant EPHX2 |
| Does overexpression of EPHX1 protect against carcinogens? | EPHX1-overexpressing cell lines |
| What is the effect of sEH inhibition on neuroinflammation? | Primary microglia treated with sEH inhibitors |
| Can tagged EPHX2 reveal subcellular localization? | Knock-in of FLAG-tagged EPHX2 in cell lines |
| Does CRISPR knockout of EPHX2 increase EET levels? | EPHX2 knockout iPSC-derived endothelial cells |
How to Study the epoxide hydrolase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Fluorogenic substrate assay | Epoxide hydrolase activity | High-throughput inhibitor screening |
| LC-MS/MS | EET and DHET levels | Quantification of sEH activity in biological samples |
| Western blot | Protein expression | Validation of knockout or overexpression |
| qRT-PCR | mRNA levels | Gene expression analysis |
| CRISPR/Cas9 knockout | Loss-of-function phenotype | Studying gene function in cell models |
| Directed evolution | Enzyme variants with improved properties | Biocatalyst engineering |
| Molecular docking | Substrate-enzyme interactions | Rational design of inhibitors |
| Immunofluorescence | Subcellular localization | Tagged protein imaging |
Enzymatic activity assays
Epoxide hydrolase activity is commonly measured using fluorogenic or chromogenic substrates such as trans-stilbene oxide or cyano(6-methoxy-naphthalen-2-yl)methyl ester. These assays monitor the formation of diol products via fluorescence or absorbance. For sEH, the hydrolysis of EETs to DHETs can be quantified by LC-MS/MS.
Inhibitor screening
Natural product extracts and synthetic compounds are screened for sEH inhibitory activity using in vitro enzyme assays. For example, components of Glycyrrhiza uralensis were tested for sEH inhibition, leading to the identification of active flavonoids. Similarly, anthraquinones from Aloe were evaluated for sEH inhibition.
Genetic manipulation and expression analysis
CRISPR/Cas9 knockout of EPHX2 or EPHX1 in cell lines allows study of loss-of-function phenotypes. Overexpression via lentiviral vectors enables gain-of-function studies. Quantitative PCR and Western blotting are used to confirm expression changes.
Structural and biophysical methods
X-ray crystallography and molecular docking provide insights into substrate binding and catalytic mechanism. Directed evolution studies have used structural data to engineer epoxide hydrolases with improved activity and enantioselectivity.
How CRISPR Can Be Used to Study GO:0004301 epoxide hydrolase activity
Knockout
CRISPR/Cas9-mediated knockout of EPHX2 or EPHX1 creates cell models to study the consequences of loss of epoxide hydrolase activity. For example, EPHX2 knockout cells show elevated EET levels and altered inflammatory responses. These models are valuable for validating drug targets and understanding disease mechanisms.
Point Mutation
Introducing specific point mutations in EPHX2 via CRISPR base editing or homology-directed repair allows researchers to dissect catalytic residues or regulatory phosphorylation sites. Such models can reveal how mutations affect enzyme activity and substrate specificity.
Knock-in
Knock-in of tagged EPHX2 (e.g., FLAG or GFP) enables real-time tracking of protein localization and interaction. This approach is useful for studying sEH dynamics under different conditions. Knock-in of disease-associated variants can also model human polymorphisms.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of EPHX1 or EPHX2 can be used to study gain-of-function effects. Overexpression models help determine whether increased epoxide hydrolase activity exacerbates or protects against disease phenotypes.
How EDITGENE Supports epoxide hydrolase activity Research
Researchers studying epoxide hydrolase activity-related genes often need to determine whether a candidate gene is causally involved in a specific phenotype, such as inflammation or drug metabolism. This requires precise genetic models that can knockout, mutate, or overexpress the gene of interest in relevant cell types. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate such investigations.
Contact EDITGENE today to design your custom CRISPR model for epoxide hydrolase activity research.
Frequently Asked Questions About epoxide hydrolase activity
What is epoxide hydrolase activity?
Epoxide hydrolase activity (GO:0004301) is the catalysis of the reaction: an epoxide + H2O = an ethanediol. It is a molecular function that hydrolyzes epoxide rings to diols.
What genes are involved in epoxide hydrolase activity?
Key genes include EPHX1 (microsomal epoxide hydrolase), EPHX2 (soluble epoxide hydrolase), and other EPHX family members. Cytochrome P450 genes such as CYP2C8 and CYP2J2 produce epoxide substrates.
What diseases are associated with epoxide hydrolase activity?
Dysregulation is linked to cardiovascular diseases, hypertension, inflammation, neuroinflammation, and cancer susceptibility.
How is epoxide hydrolase activity measured?
It is measured using fluorogenic substrates, LC-MS/MS for lipid metabolites, or coupled assays. Inhibitor screening often uses purified enzyme and fluorescent probes.
What are inhibitors of soluble epoxide hydrolase?
Natural compounds from Glycyrrhiza uralensis and Aloe, as well as synthetic inhibitors like AUDA and TPPU, inhibit sEH activity.
Can epoxide hydrolase activity be studied with CRISPR?
Yes, CRISPR knockout, knock-in, and overexpression models allow precise manipulation of EPHX genes to study their function in disease.
What is the role of soluble epoxide hydrolase in inflammation?
sEH hydrolyzes anti-inflammatory EETs to less active DHETs; inhibiting sEH increases EETs and reduces inflammation.
Is epoxide hydrolase activity involved in neuroinflammation?
Yes, sEH inhibition has shown neuroprotective effects in models of neuroinflammation, partly through modulation of lipid mediators.
What are the substrates of epoxide hydrolase?
Substrates include xenobiotic epoxides, epoxy-fatty acids (e.g., EETs), and trans-stilbene oxide. Specificity varies among enzyme isoforms.
How can I create a knockout of EPHX2 in my lab?
EDITGENE provides custom CRISPR/Cas9 knockout services for EPHX2 and related genes in various cell types, with full validation.
Conclusion
Epoxide hydrolase activity (GO:0004301) is a fundamental enzymatic function with broad implications in detoxification, lipid signaling, and disease. The soluble epoxide hydrolase EPHX2 is a well-validated drug target for cardiovascular and inflammatory conditions, while EPHX1 plays a key role in xenobiotic metabolism. Advances in CRISPR-based models and enzyme engineering continue to illuminate the mechanistic details and therapeutic potential of this activity. Researchers can leverage EDITGENE's services to generate precise genetic models and accelerate discoveries in this field.
References
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- 3. Kim JH et al.. 2023. Inhibition of Soluble Epoxide Hydrolase Activity by Components of Glycyrrhiza uralensis.. Int J Mol Sci 24(7) PMID: 37047457
- 4. Salvi HM et al.. 2021. Organic-inorganic epoxide hydrolase hybrid nanoflowers with enhanced catalytic activity: Hydrolysis of styrene oxide to 1-phenyl-1,2-ethanediol.. J Biotechnol 341:113-120 PMID: 34536457
- 5. Meijer J et al.. 1988. Cytosolic epoxide hydrolase.. Chem Biol Interact 64(3):207-49 PMID: 3277731
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- 7. Glatt H et al.. 1980. Epoxide hydrolase activity in native and in mitogen-stimulated lymphocytes of various human donors.. Cancer Res 40(7):2552-6 PMID: 7388811
- 8. Zhang J et al.. 2025. Targeting PBK with small-molecule 1-O-acetyl-4R,6S-britannilactone for the treatment of neuroinflammation.. Proc Natl Acad Sci U S A 122(29):e2502593122 PMID: 40658838
