Copper(I) transfer into metallothionein mediated by glutathione

A. M. Da Costa Ferreira, M. R. Ciriolo, L. Marcocci, G. Rotilio

Research output: Contribution to journalArticle

Abstract

Rabbit liver metallothionein depleted of Cd(II) and Zn(II) was fully reconstituted using a Cu(I)-GSH complex under strictly anaerobic conditions. Anaerobic fluorescence titration, using an emission band at 625 nm which is diagnostic of the correct insertion of Cu(I) into the thiolate clusters of metallothionein, showed that the fluorescence maximum was obtained on addition of as many Cu(I) equivalents as the available Cu(I)-binding sites in the protein (i.e. 12). Binding was nearly complete within 1 min, and Cu(I)-GSH was much more efficient than Cu(I)-thiourea or Cu(I)-acetonitrile in metallothionein reconstitution. In air, full reconstitution was obtained with stoichiometric copper only when an excess of GSH was present in the reaction mixture Cu(I)-GSH was also able to displace Zn(II) and Cd(II) from natural metallized thionein. It is concluded that: (a) Cu(I)-GSH is a potential physiological Cu(I) carrier, not only for Cu2+/Zn2+ superoxide dismutase but also for metallothionein; (b) in the case of metallothionein, physiological concentrations of GSH protect the protein from autoxidation in air and facilitate Cu(I)-thiolate exchange; (c) the natural metal composition of metallothionein may be related to metal bioavailability rather than to evolutionary changes in protein structure.

Original languageEnglish
Pages (from-to)673-676
Number of pages4
JournalBiochemical Journal
Volume292
Issue number3
Publication statusPublished - 1993

ASJC Scopus subject areas

  • Biochemistry

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    Da Costa Ferreira, A. M., Ciriolo, M. R., Marcocci, L., & Rotilio, G. (1993). Copper(I) transfer into metallothionein mediated by glutathione. Biochemical Journal, 292(3), 673-676.