Metal regulation of metallothionein participation in redox reactions

Like glutathione or dithiothreitol, metallothionein effects the formation o f pancreatic ribonuclease A from its S-sulfonated derivative catalyzed by p rotein disulfide isomerase, EDTA increases the yield of ribonuclease A acti vity recovery with metallothionein but does not affect the reaction with gl utathione or dithiothreitol, EDTA also increases the reactivity of thiol gr oups in metallothionein with 5,5'-dithiobis-(2-nitrobenzoic acid) by chelat ion of zinc ions, It is suggested that the thiol groups in metallothionein form a part of the pool of cellular thiols in the regulation of cellular re dox reactions and their availability is modulated by zinc chelation, (C) 19 99 Federation of European Biochemical Societies.