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Cisplatin binding sites on human albumin
A I Ivanov1, J Christodoulou, J A Parkinson
1Department of Chemistry, University of Edinburgh, Edinburgh EH9 3JJ, United Kingdom.
The Journal of Biological Chemistry
|June 17, 1998
Summary
Cisplatin anticancer drug metabolism involves reactions with albumin. New findings show methionine, not cysteine, is the primary binding site, influencing drug activity and ammonia release.
Area of Science:
- Biochemistry
- Medicinal Chemistry
- Pharmacology
Background:
- Cisplatin is a crucial anticancer drug.
- Albumin plays a key role in cisplatin metabolism.
- Understanding these interactions is vital for drug efficacy.
Purpose of the Study:
- To elucidate the binding sites and reaction mechanisms of cisplatin with albumin.
- To investigate the role of specific amino acid residues in these interactions.
- To clarify the impact on cisplatin's biological activity.
Main Methods:
- 15N-labeled cisplatin and 2D 1H,15N NMR spectroscopy.
- Comparison of natural and recombinant human serum albumin.
- Chemical modification of albumin residues (Cys, Met, His).
- Thiourea reaction assays and gel filtration chromatography.
Main Results:
- Identified methionine (Met) as the major sulfur-containing binding site, forming an S,N macrochelate, contrary to prior Cys-34 focus.
- Observed additional adducts at other Met residues and Cys-34.
- Demonstrated ammonia (NH3) release due to Met's trans influence, leading to protein cross-linking.
Conclusions:
- Methionine residues are critical for cisplatin binding to albumin, forming macrochelates.
- Ammonia release and protein cross-linking impact cisplatin's pharmacokinetic and pharmacodynamic profile.
- These findings necessitate a re-evaluation of cisplatin-albumin complex formation and its biological consequences.