Damages to Zn2+and Cd2+ complexes of a metallothionein (MT) from a plant (Quercus suber - Qs), due to radicai stress exposure, were investigated. QsMT, obtained by in vivo synthesis, is a low-molecular weight cysteine-rich protein with high capacity for binding metal ions. Although MTs do not appear to be essential for life, there is mounting evidences for a survival advantage of MT in situations of stress, including exposure to radicals and toxic metals. Gamma-irradiation was used to simulate the conditions of an endogenous radical stress. The degradation of the metal complexes was followed by Raman spectroscopy and the occurrence of tandem protein/lipid damage was shown by using a biomimetic model based on unsaturated lipid vesicle suspensions. The H1 and eaq- attacks on the metal-QsMT aggregates are able to induce significant structural changes such as partial deconstruction and/or rearrangement of the metal clusters, and breaking of the protein backbone. Sulfur-containing residues resulted to be selectively attacked; in particular, Cys resulted to be among the most sensitive residues towards radical attack, suggesting that the thiolate clusters of both metal-QsMTs act as efficient interceptors of reducing species. Under reductive stress Zn-QsMT undergoes a significant thiolate group oxidation. The participation of His to metal coordination became necessary for protein stabilization after radical stress. The radical-induced effects were dependent on the divalent metal bound. The reactions of reductive reactive species with Met residues and/or sulfur-containing ligands afford diffusible sulfur-centered radicals, which migrate from the aqueous phase to the lipid bilayer and transform the cis doublé bond of thè oleate moiety to the trans isomer.
Titolo: | Metal complexes of a plant metallothionein under radical stress: assessment of structural modifications and transfer of radical damage. |
Autore/i: | A. Torreggiani; C. Ferreri; TINTI, ANNA; S. Atrian; M. Capdevila; C. Chatgilialoglu |
Autore/i Unibo: | |
Anno: | 2009 |
Titolo del libro: | Abstract book XIII European Conference on the Spectroscopy of Biological Molecules |
Pagina iniziale: | PB88 |
Pagina finale: | PB88 |
Abstract: | Damages to Zn2+and Cd2+ complexes of a metallothionein (MT) from a plant (Quercus suber - Qs), due to radicai stress exposure, were investigated. QsMT, obtained by in vivo synthesis, is a low-molecular weight cysteine-rich protein with high capacity for binding metal ions. Although MTs do not appear to be essential for life, there is mounting evidences for a survival advantage of MT in situations of stress, including exposure to radicals and toxic metals. Gamma-irradiation was used to simulate the conditions of an endogenous radical stress. The degradation of the metal complexes was followed by Raman spectroscopy and the occurrence of tandem protein/lipid damage was shown by using a biomimetic model based on unsaturated lipid vesicle suspensions. The H1 and eaq- attacks on the metal-QsMT aggregates are able to induce significant structural changes such as partial deconstruction and/or rearrangement of the metal clusters, and breaking of the protein backbone. Sulfur-containing residues resulted to be selectively attacked; in particular, Cys resulted to be among the most sensitive residues towards radical attack, suggesting that the thiolate clusters of both metal-QsMTs act as efficient interceptors of reducing species. Under reductive stress Zn-QsMT undergoes a significant thiolate group oxidation. The participation of His to metal coordination became necessary for protein stabilization after radical stress. The radical-induced effects were dependent on the divalent metal bound. The reactions of reductive reactive species with Met residues and/or sulfur-containing ligands afford diffusible sulfur-centered radicals, which migrate from the aqueous phase to the lipid bilayer and transform the cis doublé bond of thè oleate moiety to the trans isomer. |
Data prodotto definitivo in UGOV: | 12-feb-2010 |
Appare nelle tipologie: | 4.02 Riassunto (Abstract) |