Glutathione (GSH) is a tripeptide composed of glutamate, cysteine, and glycine (γ-L-glutamyl-L-cysteinyl-glycine). Often called the "master antioxidant," it is the most abundant intracellular thiol compound and essential for cellular defense against oxidative stress. Chemical Formula: C₁₀H₁₇N₃O₆S Molecular Weight: 307.32 g/mol Structure: γ-glutamyl-cysteinyl-glycine Active Group: Cysteine sulfhydryl (-SH) group The unique γ-peptide bond between glutamate and cysteine protects GSH from common peptidases. - Neutralizes reactive oxygen species, free radicals, peroxides, and lipid peroxides - The cysteine thiol donates electrons to reduce oxidants - GSH is oxidized to GSSG (glutathione disulfide) in the process - Glutathione reductase regenerates GSH from GSSG using NADPH - Glutathione Peroxidase (GPx): Catalyzes GSH-dependent reduction of H₂O₂ - Glutathione S-Transferase (GST): Conjugates GSH to electrophiles for detoxification - Glutaredoxin: Uses GSH for thiol-disulfide exchange reactions Post-translational modification that protects protein cysteines from irreversible oxidation while regulating signal transduction pathways. | Location | Concentration | Function | |----------|---------------|----------| | Cytoplasm | 0.5-10 mM (80-85%) | Primary redox buffer | | Mitochondria | 10-15% of cellular GSH | Regulates apoptosis | | Nucleus | Variable | Cell division, DNA synthesis | | Extracellular | 2-20 μM | Limited antioxidant capacity | In healthy cells, >90% exists as reduced GSH, with <10% as oxidized GSSG. Step 1 - γ-Glutamylcysteine Ligase (GCL): - Glutamate + Cysteine → γ-Glutamylcysteine - Rate-limiting enzyme regulated by Nrf2 - Feedback inhibited by GSH Step 2 - Glutathione Synthetase (GS): - γ-Glutamylcysteine + Glycine → GSH | Application | Focus Area | Key Findings | |-------------|------------|--------------| | Oxidative Stress | GSH/GSSG ratio as biomarker | Critical indicator of cellular redox status | | Neuroscience | Parkinson's research | Low GSH in substantia nigra correlates with severity | | Cancer | Dual role | Chemopreventive vs. tumor-promoting in cancer cells | | Aging | Inflammaging | GSH depletion associated with aging | | Toxicology | Xenobiotic detox | Phase II metabolism via mercapturic acid pathway | - Dual role: Removes carcinogens (protective) vs. elevated in cancer cells (pro-survival) - Drug resistance: High GSH levels confer chemotherapy resistance - Therapeutic targeting: GSH inhibitors (e.g., BSO) sensitize cancer cells - Parkinson's disease: Reduced substantia nigra GSH - N-acetylcysteine (NAC) therapy: Precursor to boost brain GSH - Mitochondrial GSH critical for neuronal protection | Application | Tool/Compound | |-------------|---------------| | GSH supplementation | Glutathione reduced ethyl ester | | GSH depletion | Buthionine sulfoximine (BSO) | | GSH precursor | N-acetylcysteine (NAC) | | Protein purification | Glutathione-Sepharose resins | | GSH detection | ThiolTracker, m
Glutathione: Master Antioxidant Research Guide
Comprehensive overview of Glutathione, the body's primary intracellular antioxidant tripeptide essential for cellular redox homeostasis, detoxification, and immune function.