Glutathione biosynthetic enzymes (GCL/GSS)

Glutathione biosynthetic enzymes, primarily comprising glutamate-cysteine ligase (GCL) and glutathione synthetase (GSS), are the essential catalysts for the de novo synthesis of glutathione (GSH), the most abundant non-protein thiol and a master antioxidant in eukaryotic cells (Lu, 2013, PMID: 23429014). GCL, the rate-limiting enzyme, is a heterodimer consisting of a catalytic (GCLC) and a modifier (GCLM) subunit that facilitates the formation of gamma-glutamylcysteine from glutamate and cysteine (Franklin et al., 2009, PMID: 19149604). GSS subsequently catalyzes the addition of glycine to gamma-glutamylcysteine to produce the final tripeptide, GSH (Ristoff & Larsson, 2007, PMID: 17306134). These enzymes are critical for maintaining cellular redox homeostasis, detoxifying electrophilic xenobiotics, and regulating various signaling pathways related to cell survival and apoptosis (Traverso et al., 2013, PMID: 23630461). In oncology, many tumors overexpress these enzymes to counteract high levels of reactive oxygen species and develop resistance to platinum-based drugs and radiation, making GCL a significant target for chemosensitization (Harris et al., 2015, PMID: 25833140). Pharmacological inhibition of GCL by agents like buthionine sulfoximine (BSO) has been explored in clinical trials to deplete GSH and enhance the efficacy of pro-oxidant therapies (O'Dwyer et al., 1996, PMID: 8631031).

Other names

Glutamate-cysteine ligaseGlutathione synthetaseGamma-glutamylcysteine synthetaseGCSGCLGSSGSH biosynthetic pathway

Inhibition of the rate-limiting enzyme glutamate-cysteine ligase (GCL) to deplete intracellular glutathione levels, thereby increasing cellular sensitivity to oxidative stress and chemotherapeutic agents.