GO:0004362 glutathione-disulfide reductase (NADPH) activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004362 describes the molecular function of glutathione-disulfide reductase (NADPH) activity, which catalyzes the reduction of glutathione disulfide (GSSG) to two molecules of reduced glutathione (GSH) using NADPH as the electron donor.
• This activity is essential for maintaining the cellular reduced glutathione pool, protecting cells from oxidative stress and regulating redox signaling [1,4].
• The enzyme is a homodimeric flavoprotein that uses FAD as a prosthetic group and cycles between oxidized and reduced states via NADPH-dependent hydride transfer [2,8].
• Glutathione reductase is a validated drug target in parasitic infections, and its inhibition can disrupt redox balance in pathogens and cancer cells [5,6,7].
• Defects in glutathione reductase activity are linked to hemolytic anemia, cancer progression, and neurodegenerative conditions [1,4].
• CRISPR-based knockout, knock-in, and overexpression models enable precise dissection of glutathione reductase function in health and disease [3,8].
Description
Glutathione-disulfide reductase (NADPH) activity, encoded by GO:0004362, is a fundamental molecular function that maintains the cellular redox environment by regenerating reduced glutathione (GSH) from its oxidized form, glutathione disulfide (GSSG). This activity is catalyzed by glutathione reductase (GSR), an enzyme that utilizes NADPH as a reducing equivalent to break the disulfide bond in GSSG, producing two GSH molecules and NADP+. The reaction is critical for antioxidant defense, detoxification, and redox signaling, and its dysregulation is implicated in a wide range of pathologies, including hemolytic disorders, cancer, and neurodegeneration [1,4]. Researchers study GO:0004362 to understand how cells cope with oxidative stress, how pathogens maintain redox homeostasis, and how metabolic reprogramming in cancer alters glutathione metabolism [3,5]. The enzyme is also a target for antimalarial and antiparasitic drug development, as inhibition of glutathione reductase can selectively kill parasites that rely heavily on glutathione for survival [5,6,7]. In this article, we provide a comprehensive overview of the definition, mechanism, key genes, disease associations, and research methods for studying glutathione-disulfide reductase (NADPH) activity, with a focus on CRISPR-based models and EDITGENE services.
glutathione-disulfide reductase (NADPH) activity At A Glance
| GO ID | GO:0004362 |
|---|---|
| GO term | glutathione-disulfide reductase (NADPH) activity |
| Ontology | molecular_function |
| Synonym | glutathione reductase activity; GSSG reductase activity; NADPH-glutathione reductase activity; glutathione:NADP+ oxidoreductase activity |
| Major function | Reduction of glutathione disulfide (GSSG) to reduced glutathione (GSH) using NADPH |
| Reaction | 2 glutathione + NADP+ = glutathione disulfide + NADPH + H+ |
| Cofactor | FAD (flavin adenine dinucleotide) |
| EC number | 1.8.1.7 |
| Localization | Cytoplasm, mitochondria, and other cellular compartments |
What Is GO:0004362?
GO:0004362 glutathione-disulfide reductase (NADPH) activity is defined as the catalysis of the reaction: 2 glutathione + NADP+ = glutathione disulfide + NADPH + H+. In other words, it is the enzyme activity that reduces oxidized glutathione (GSSG) back to its reduced form (GSH) using NADPH as the electron donor, thereby maintaining the cellular redox balance [1,2].
Why Is glutathione-disulfide reductase (NADPH) activity Important in Cell Biology?
Glutathione-disulfide reductase (NADPH) activity is a cornerstone of cellular antioxidant defense and redox homeostasis. By regenerating GSH, it ensures that cells can neutralize reactive oxygen species (ROS), detoxify xenobiotics, and maintain the reduced environment necessary for protein function and signaling [1,4]. Its importance extends to infectious diseases, where parasite glutathione reductases are potential drug targets [5,6,7], and to cancer, where altered glutathione metabolism contributes to chemoresistance and tumor progression. Understanding this activity is therefore critical for basic biology, drug discovery, and clinical research.
• Maintains the cellular pool of reduced glutathione (GSH), a major antioxidant.
• Protects cells from oxidative stress and prevents oxidative damage to lipids, proteins, and DNA.
• Regulates redox-sensitive signaling pathways and gene expression.
• Supports detoxification of xenobiotics and drugs by maintaining GSH levels.
• Is a validated target for antimalarial and antiparasitic drugs [5,6,7].
• Plays a role in cancer cell survival and resistance to chemotherapy.
• Deficiency or inhibition leads to hemolytic anemia and other blood disorders.
• Involved in neurodegenerative diseases where oxidative stress is a key factor.
• Essential for pathogen survival, making it a potential antimicrobial target.
• Provides a model system for studying enzyme kinetics and redox biochemistry.
What Happens During glutathione-disulfide reductase (NADPH) activity?
Substrate Binding and Hydride Transfer
In simple terms: The enzyme grabs NADPH and passes its electrons to a helper molecule called FAD.
Glutathione reductase is a homodimeric flavoprotein. Each subunit binds one FAD molecule and one NADPH. The catalytic cycle begins with the binding of NADPH, which reduces the FAD prosthetic group by transferring a hydride ion. This step is essential for the subsequent reduction of the disulfide bond in glutathione disulfide (GSSG) [2,8].
Reduction of Glutathione Disulfide (GSSG)
In simple terms: The enzyme breaks the disulfide bond in GSSG, turning it back into two molecules of reduced glutathione.
After FAD is reduced, the enzyme binds GSSG. The reduced FAD transfers electrons to the disulfide bond of GSSG, cleaving it and releasing two molecules of reduced glutathione (GSH). This reaction is highly specific for GSSG and requires the enzyme to undergo conformational changes to accommodate the substrate [1,2].
NADP+ Release and Enzyme Regeneration
In simple terms: The used-up NADP+ leaves, and the enzyme is ready to start again.
Following the reduction of GSSG, the oxidized NADP+ is released from the enzyme, allowing the enzyme to return to its initial state and participate in another catalytic cycle. The overall reaction is: 2 GSH + NADP+ = GSSG + NADPH + H+, but in the physiological direction, it catalyzes the reverse: GSSG + NADPH + H+ = 2 GSH + NADP+ [1,2].
Role of FAD Cofactor
In simple terms: FAD acts as a temporary electron carrier inside the enzyme.
FAD is tightly bound to glutathione reductase and serves as an intermediate electron acceptor/donor. It accepts electrons from NADPH and donates them to GSSG. The redox state of FAD can be monitored spectrophotometrically, which is the basis for standard enzyme activity assays [2,8].
Dimerization and Structural Stability
In simple terms: Two identical subunits come together to form the active enzyme.
Glutathione reductase functions as a homodimer, with each subunit containing an active site. Dimerization is essential for catalytic activity and stability. The dimer interface contributes to the overall structure and may regulate enzyme activity through allosteric interactions.
Key Genes Involved in GO:0004362 glutathione-disulfide reductase (NADPH) activity
The following genes and proteins are directly involved in or closely associated with glutathione-disulfide reductase (NADPH) activity.
| Gene | Major Role | Research Relevance |
|---|---|---|
| GSR | Encodes glutathione reductase, the enzyme catalyzing GO:0004362 | Central to redox homeostasis; knockout causes oxidative stress sensitivity |
| G6PD | Generates NADPH via pentose phosphate pathway | Supplies NADPH for glutathione reductase; inhibition activates G6PD |
| GPX1 | Glutathione peroxidase, reduces H2O2 using GSH | Works with GSR to detoxify peroxides; GSH is regenerated by GSR |
| GCLC | Catalyzes first step of glutathione synthesis | Provides GSH; feedback with GSR maintains GSH/GSSG ratio |
| GCLM | Modulatory subunit of glutamate-cysteine ligase | Regulates GSH synthesis; affects GSR substrate availability |
| GSS | Glutathione synthetase, second step of GSH synthesis | Essential for GSH production; GSR recycles GSSG |
| TXN | Thioredoxin, another disulfide reductase system | Cross-talk with GSR in redox regulation |
| TXNRD1 | Thioredoxin reductase, NADPH-dependent | Parallel system to GSR; can compensate in some contexts |
| NQO1 | NAD(P)H:quinone oxidoreductase | Redox cycling and antioxidant defense; interacts with GSH system |
| SLC7A11 | Cystine/glutamate antiporter, supplies cysteine for GSH | Regulates GSH synthesis; affects GSR activity indirectly |
| NFE2L2 | Nrf2 transcription factor, regulates antioxidant genes | Controls expression of GSR and other antioxidant enzymes |
| PRDX1 | Peroxiredoxin, reduces peroxides using thioredoxin | Redox network member; interacts with GSH system |
| SOD1 | Superoxide dismutase, converts superoxide to H2O2 | Upstream of GSH system; GSR helps detoxify H2O2 via GPX |
| CAT | Catalase, detoxifies H2O2 | Complementary to GSH system in peroxide removal |
| TP53 | Tumor suppressor, regulates redox genes | Mutant p53 can alter GSH metabolism and GSR expression |
| HIF1A | Hypoxia-inducible factor, regulates metabolic genes | May influence NADPH production and GSR activity |
| KEAP1 | Negative regulator of Nrf2 | Mutations activate Nrf2, increasing GSR expression |
| PARP1 | DNA repair enzyme, consumes NAD+ | NAD+ depletion can affect NADPH supply for GSR |
How Is glutathione-disulfide reductase (NADPH) activity Regulated?
Glutathione-disulfide reductase (NADPH) activity is regulated at multiple levels. Transcriptionally, the GSR gene is a target of Nrf2 (NFE2L2), which induces antioxidant response element (ARE)-driven expression under oxidative stress. Post-translationally, the enzyme can be modified by oxidation, nitrosylation, or phosphorylation, affecting its activity. Additionally, the availability of NADPH, primarily generated by glucose-6-phosphate dehydrogenase (G6PD) and malic enzyme, tightly controls GSR flux. Inhibition of GSR can lead to compensatory activation of G6PD to maintain NADPH levels. Furthermore, the cellular GSH/GSSG ratio provides feedback regulation, as high GSSG levels stimulate GSR activity.
glutathione-disulfide reductase (NADPH) activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| GSR | Hemolytic anemia due to GSR deficiency | GSR knockout mice or patient-derived iPSCs |
| GSR | Cancer chemoresistance | Cancer cell lines with GSR overexpression or knockout |
| G6PD | G6PD deficiency with impaired NADPH supply | G6PD knockout cells, patient fibroblasts |
| GPX1 | Oxidative stress-related diseases | GPX1 knockout mice |
| NFE2L2 | Cancer and chronic obstructive pulmonary disease | Nrf2 knockout or Keap1 mutant models |
Glutathione Reductase Deficiency and Hemolytic Anemia
Deficiency in glutathione reductase activity, often due to genetic mutations in GSR or acquired factors like riboflavin deficiency, leads to impaired GSH regeneration and increased oxidative stress in red blood cells. This can cause hemolytic anemia, characterized by premature destruction of erythrocytes. Patients with GSR deficiency may present with jaundice, fatigue, and splenomegaly, and the condition can be exacerbated by oxidative drugs or infections.
Cancer and Chemoresistance
Many cancer cells exhibit elevated glutathione reductase activity to maintain high GSH levels, which protects them from oxidative stress and contributes to resistance to chemotherapy and radiotherapy. Inhibition of GSR can sensitize cancer cells to oxidative damage and overcome chemoresistance. Furthermore, mutant p53 can upregulate GSR expression, promoting tumor survival.
Parasitic Infections and Drug Targeting
Parasites such as Plasmodium falciparum, Leishmania infantum, and Haemonchus contortus rely heavily on glutathione reductase for redox balance and survival. The enzyme is a validated drug target, and inhibitors like 1,4-naphthoquinones have shown antimalarial activity [5,6,7]. The unique structural features of parasite GSRs can be exploited for selective inhibition.
Neurodegenerative Diseases
Oxidative stress is a hallmark of neurodegenerative diseases such as Alzheimer's and Parkinson's. Reduced glutathione reductase activity and lower GSH levels are observed in affected brain regions, contributing to neuronal damage. Enhancing GSR activity or GSH levels is a potential therapeutic strategy.
From glutathione-disulfide reductase (NADPH) activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does GSR knockout increase oxidative stress? | GSR knockout cell lines (e.g., HeLa, HEK293) via CRISPR |
| How does a point mutation in GSR active site affect catalysis? | CRISPR knock-in of mutant GSR (e.g., Cys-to-Ser) in cell lines |
| Can GSR overexpression protect against oxidative damage? | GSR overexpression stable cell lines |
| What is the role of GSR in cancer drug resistance? | GSR knockout or overexpression in cancer cells followed by drug treatment |
| How does GSR interact with other redox proteins? | Knock-in of tagged GSR (e.g., FLAG, GFP) for co-IP and imaging |
| Can GSR inhibitors selectively kill parasites? | Parasite cell lines with GSR knockout or knockdown |
How to Study the glutathione-disulfide reductase (NADPH) activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| NADPH oxidation assay | Glutathione reductase enzyme activity | Kinetic studies, inhibitor screening |
| GSH/GSSG ratio assay | Cellular redox status | Oxidative stress assessment |
| CRISPR knockout | Loss of gene function | Studying GSR role in stress response |
| CRISPR knock-in | Introduction of specific mutations | Structure-function analysis of GSR |
| Western blot | Protein expression levels | Validation of knockout/overexpression |
| RNA-seq | Transcriptional changes | Global response to GSR modulation |
| Co-immunoprecipitation | Protein-protein interactions | Identifying GSR binding partners |
| High-throughput screening | Identification of small molecule inhibitors | Drug discovery for parasitic diseases |
Enzyme Activity Assays
Glutathione reductase activity is commonly measured spectrophotometrically by monitoring the oxidation of NADPH at 340 nm. The assay mixture contains GSSG, NADPH, and cell lysate; the decrease in absorbance is proportional to enzyme activity. This method is robust and suitable for high-throughput screening of inhibitors or genetic variants.
Genetic Knockout and Knockdown
CRISPR-Cas9-mediated knockout of GSR or other redox genes allows researchers to study the consequences of loss of glutathione reductase activity on cellular redox balance, proliferation, and stress responses [3,8]. Lentiviral shRNA knockdown provides an alternative for transient studies.
Redox State Measurements
The GSH/GSSG ratio is a key indicator of cellular redox status. It can be measured using enzymatic recycling assays, HPLC, or fluorescent probes. These methods help assess the impact of GSR modulation on overall redox homeostasis [1,4].
Proteomics and Interactomics
Affinity purification coupled with mass spectrometry (AP-MS) using tagged GSR can identify interacting proteins and post-translational modifications. This approach reveals the broader redox network and potential regulatory mechanisms.
How CRISPR Can Be Used to Study GO:0004362 glutathione-disulfide reductase (NADPH) activity
Knockout
CRISPR-Cas9 knockout of GSR generates cell lines completely lacking glutathione reductase activity. These models are invaluable for studying the cellular response to oxidative stress, the role of GSR in drug resistance, and compensatory mechanisms involving other redox systems [3,8]. Knockout cells typically show increased sensitivity to oxidants and altered GSH/GSSG ratios.
Point Mutation
CRISPR knock-in of specific point mutations in the GSR active site (e.g., catalytic cysteine residues) allows precise dissection of the catalytic mechanism and the contribution of individual amino acids to enzyme function. Such models can reveal how mutations affect substrate binding, FAD interaction, and overall activity.
Knock-in
Knock-in of tagged GSR (e.g., FLAG, HA, or GFP) enables visualization, affinity purification, and interaction studies. Tagged GSR can be used to monitor enzyme localization, dynamics, and complex formation in live cells, providing insights into its regulation and function.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of GSR increases glutathione reductase activity, which can protect cells from oxidative damage and confer resistance to certain drugs. Overexpression models are useful for studying the protective role of GSR in neurodegeneration and cancer [3,4].
How EDITGENE Supports glutathione-disulfide reductase (NADPH) activity Research
Researchers studying glutathione-disulfide reductase (NADPH) activity-related genes often need to determine whether a candidate gene is causally involved in redox regulation, disease progression, or drug response. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate this research, from knockout and point mutation to knock-in and overexpression, along with library screening and bioinformatics support.
Contact EDITGENE today to design your custom CRISPR model for glutathione-disulfide reductase (NADPH) activity research.
Frequently Asked Questions About glutathione-disulfide reductase (NADPH) activity
What is glutathione-disulfide reductase (NADPH) activity?
It is the enzyme activity that reduces oxidized glutathione (GSSG) to reduced glutathione (GSH) using NADPH, encoded by GO:0004362.
What genes are involved in glutathione-disulfide reductase (NADPH) activity?
The primary gene is GSR, which encodes glutathione reductase. Other genes like G6PD, GPX1, and NFE2L2 support or regulate this activity [3,4].
What is the role of glutathione reductase in oxidative stress?
It maintains the cellular pool of reduced glutathione, which neutralizes reactive oxygen species and protects cells from oxidative damage [1,4].
How is glutathione reductase activity measured?
It is typically measured by a spectrophotometric assay monitoring NADPH oxidation at 340 nm.
What diseases are associated with glutathione reductase deficiency?
Deficiency can cause hemolytic anemia, and altered activity is linked to cancer and neurodegenerative diseases [1,4].
Is glutathione reductase a drug target?
Yes, it is a validated target for antimalarial and antiparasitic drugs, and inhibitors are being explored for cancer therapy [5,6,7].
What is the difference between GSH and GSSG?
GSH is reduced glutathione, an antioxidant; GSSG is oxidized glutathione disulfide. Glutathione reductase converts GSSG back to GSH.
How does NADPH affect glutathione reductase?
NADPH provides the reducing power for the reaction; without it, the enzyme cannot regenerate GSH.
Can CRISPR be used to study glutathione reductase?
Yes, CRISPR knockout, knock-in, and overexpression models are powerful tools to dissect GSR function in cells [3,8].
What are the symptoms of glutathione reductase deficiency?
Symptoms include jaundice, fatigue, and anemia due to increased oxidative stress in red blood cells.
Conclusion
Glutathione-disulfide reductase (NADPH) activity (GO:0004362) is a critical molecular function that safeguards cellular redox balance by regenerating reduced glutathione. Its dysregulation is implicated in hemolytic anemia, cancer, and parasitic infections, making it a compelling target for therapeutic intervention. Advances in CRISPR-based genome editing now allow precise manipulation of GSR and related genes, enabling researchers to uncover novel insights into redox biology and disease mechanisms. EDITGENE's comprehensive services support these efforts, from custom knockout and knock-in models to high-throughput screening and bioinformatics.
References
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- 3. González-Blanco A et al.. 2022. Inhibition of glutathione reductase uncovers the activation of NADPH-inhibited glucose-6-phosphate dehydrogenase.. Biotechnol Appl Biochem 69(4):1690-1695 PMID: 34387395
- 4. Miller CG et al.. 2019. Disulfide reductase systems in liver.. Br J Pharmacol 176(4):532-543 PMID: 30221761
- 5. Belorgey D et al.. 2013. 1,4-naphthoquinones and other NADPH-dependent glutathione reductase-catalyzed redox cyclers as antimalarial agents.. Curr Pharm Des 19(14):2512-28 PMID: 23116403
- 6. Plancarte A et al.. 2017. A new thioredoxin reductase with additional glutathione reductase activity in Haemonchus contortus.. Exp Parasitol 177:82-92 PMID: 28456691
- 7. Angiulli G et al.. 2015. Leishmania infantum trypanothione reductase is a promiscuous enzyme carrying an NADPH:O2 oxidoreductase activity shared by glutathione reductase.. Biochim Biophys Acta 1850(9):1891-7 PMID: 26033467
- 8. Sikanyika M et al.. 2019. The structure and activity of the glutathione reductase from Streptococcus pneumoniae.. Acta Crystallogr F Struct Biol Commun 75(Pt 1):54-61 PMID: 30605126
