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Year:
1997
| Volume: 5
| Issue: 4
| Pages: 183-185
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Original Article |
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KINETICS OF THE REACTIONS BETWEEN TETRACHLOROPLATINATE(II) WITH GLUTATHIONE AND THIOGLYCOLIC ACID. TOXIC SIDE EFFECTS OF PLATINUM ANTITUMOR COMPLEXES
Zivadin D. BUGARCIC, Zorica M. BUGARCIC, Milan JOKSOVIC, Vukadin LEOVAC, Vladimir BALTIC |
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DOI:
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Abstract: |
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Background: Interactions between platinum complexes and sulphur-bonding ligands are very important from biological and medicine point of view.
Methods: The reaction between tetrachloroplatinate(II) and sulphur-bonding ligands, glutathione and thioglycolic acid, has been studied by conventional spectrophotomerty in an aqueous 0.10 M hydrochloric acid as an ionic medium.
Results: The following values of the second-order rate constants, k2, were obtained at 25oC: (0.115 ± 0.03) M-1s-1, for glutathione and (0.624 ± 0.04) M-1s-1, for thioglycolic acid. The temperature dependence of the rate constants yealds acitivation parameters: DH = 38 ± 7 kJ mol-1; DS = - 125 ± 8 J K-1 mol-1, for glutathione and DH = 31 ± 2 kJ mol-1; DS = - 133 ± 7 J K-1 mol-1, for thioglycolic acid. The negative values of the entropies of activation are consistent with an associative mode of activation.
Conclusion: Nephrotoxicity is the result of inactivation of certain enzymes due to the binding of platinum to the sulphydryl groups of cysteine residues. In principle all sulphur-containing biomolecules, such as glutathione, methionine or cysteine could inactivate platinum complexes. |
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Key words:
Platinum(II); Complex; Thiol group; Glutathion; Thoglycolic acid; Mechanism |
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