GAMMA-GLUTAMYLCYSTEINYLGLUTAMIC ACID - A NEW HOMOLOG OF GLUTATHIONE IN MAIZE SEEDLINGS EXPOSED TO CADMIUM

Exposure of plants to Cd induces the appearance of several thiols base d on glutathione and known as class III metallothioneins (or phytochel atins). A new tripeptide with the structure gamma-GluCysGlu accumulate d in roots and shoots of Cd-exposed maize seedlings. This thiol was pu rified and identified by tandem mass spectrometry. The fragmentation p attern of the maize tripeptide was identical to that of the synthetic compound. Like glutathione, this new tripeptide may serve as a precurs or for longer-chain peptides involved in metal detoxification through the formation of Cd-binding complexes.