1H, 13C‐NMR and X‐ray Absorption Studies of Copper(I) Glutathione Complexes
Open Access
- 1 March 1996
- journal article
- Published by Wiley in European Journal of Biochemistry
- Vol. 236 (2) , 697-705
- https://doi.org/10.1111/j.1432-1033.1996.0697d.x
Abstract
The tripeptide glutathione (γ-L-Glu-L-Cys-Cly, GSH) is an important intracellular reducing agent for Cu(II) and complexation agent for Cu(I). We have studied the complexation of Cu(I) to GSH in aqueous solution at a range of pH values and Cu(I):GSH molar ratios by 1H-NMR and 13C-NMR spectroscopy and X-ray absorption spectroscopy. The NMR data are consistent with formation of a complex with approximate 1:1 stoichiometry [Cu(SG)] as the major species with only thiolate sulfur of GSH binding to Cu(I). The rate of exchange of GSH with GS-Cu was determined to be 13 s-1 at 283 K, pH 6.8. X-ray absorption spectroscopic measurements showed that Cu(I) is coordinated to 3.1 ± 0.3 sulfur atoms at approximately 0.222 nm in solutions (and solids) containing GSH: Cu in 1:1 and 2:1 mol ratios. The possible structures of polymeric Cu(I)-glutathione complexes are discussed. The high thermodynamic stability of Cu(I)-S bonds in Cu(I)-glutathione complexes coupled with their kinetic lability may provide efficient and specific pathways for the transport of copper in cells.Keywords
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