Metallothioneins

Metallothioneins are small, cysteine-rich proteins that bind divalent heavy-metal ions such as cadmium, zinc, and copper through their abundant sulfur groups. Found across animals, plants, and microorganisms, they help regulate essential metals and sequester toxic ones, protecting cells from metal-induced oxidative damage. In food science they are studied for two main reasons: as biomarkers of heavy-metal exposure in seafood and livestock, where elevated metallothionein levels signal contamination, and as potential tools for bioremediation of metal-contaminated water and soil used in food production. Their induction by cadmium and mercury also makes them useful indicators in environmental monitoring of aquaculture sites.