Cysteine

Metal Binding#

Cadmium, mercury, lead, arsenic all bind cysteine thiol groups with high affinity, depleting free cysteine and glutathione pools → Oxidative Stress.^{[1]Molecular Mechanisms of Cellular Injury and Role of Toxic Heavy Metals in Chronic Kidney DiseaseManish Mishra, Larry Nichols, Aditi A. Dave et al. · 2022Open reference 1 ↓[2]Heavy Metal Pollution in the Environment and Their Toxicological Effects on HumansBriffa J, Sinagra E, Blundell R · 2020Open reference 2 ↓}

Zinc-finger proteins use cysteine (and Histidine) residues to coordinate zinc—metal displacement at these sites is the basis of Mis-Metallation.

Iron-sulfur clusters use cysteine ligands—heavy metal disruption of iron (Fe)-S clusters is a primary toxicity mechanism.^{[3]Effects of Heavy Metals on Gut Barrier Integrity and Gut MicrobiotaSweta Ghosh, Syam P. Nukavarpu, Venkatakrishna Rao Jala · 2024Open reference 3 ↓}

Nickel: Bacterial nickel-binding proteins (Hpn, HypB) use histidine-rich motifs, but cysteine residues are critical in nickel efflux and storage proteins.^{[4]Role of Nickel in Microbial PathogenesisRobert J. Maier, Stéphane L. Benoit · 2019Open reference 4 ↓}

Microbial Context#

Gut bacteria metabolize dietary cysteine via desulfhydrase enzymes → H₂S production (Hydrogen Sulfide (H₂S)). Microbial cysteine metabolism affects the gut sulfur pool, influencing both host detoxification capacity and Desulfovibrio ecology.