ISSN:
1573-4943
Keywords:
Metallothionein
;
redox property
;
metal release
;
DsbA protein
;
fluorescence
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Mammalian metallothionein (MT) contains 20 cysteine residues involved in the two metal clusters without a disulfide bond. The redox reaction of the Cys thiols was proposed to be associated with the metal distribution of MT. The E. coli DsbA protein is extremely active in facilitating thiol/disulfide exchange both in vivo and in vitro. To further investigate the redox properties of MT, reaction between MT and DsbA was carried out in vitro by fluorescence detection. Equilibrium characterization indicates that the reaction is stoichiometric (1:1) under certain conditions. Kinetic study gives a rate constant of the redox reaction of 4.42 × 105 sec−1 M−1, which is 103-fold larger than that of glutathione reacting with DsbA. Metal-free MT (apo-MT) shows a higher equilibrium reduction potential than MT, but exhibits an indistinguishable kinetic rate. Oxidation of MT by DsbA leads to metal release from the clusters. The characteristic fluorescence increase during reduction of DsbA may provide a sensitive probe for exploring the redox properties of some reductants of biological interest. The result also implies that oxidation of Cys thiols may influence the metal release or delivery from MT.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1020654206878
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