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Cytotoxic trans-oriented platinum complexes only form adducts with single-stranded oligodeoxynucleotides.
Jo Vinje1, Francesco P Intini, Giovanni Natile
1Department of Chemistry, University of Bergen, Allègt. 41, 5007 Bergen, Norway.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|July 15, 2004
Summary
The anticancer complex trans-ethyl-ethane-diammine dichloride (trans-EE) reacts readily with single-stranded DNA but shows minimal reactivity with double-stranded DNA lacking accessible guanine residues. Steric hindrance limits trans-EE binding to solvent-exposed guanine sites in duplex DNA.
Area of Science:
- Medicinal Chemistry
- Bioinorganic Chemistry
- Molecular Biology
Background:
- Anticancer platinum complexes are crucial in chemotherapy.
- Understanding their DNA binding mechanisms is key to developing more effective drugs.
- The reactivity of different platinum complex isomers with DNA structures varies significantly.
Purpose of the Study:
- To investigate the reaction of the anticancer complex trans-[PtCl(2)[(E)-HN==C(OMe)Me](2)] (trans-EE) with single-stranded and double-stranded deoxyribonucleotides.
- To compare the DNA binding behavior of trans-EE with that of the established anticancer drug cis-[PtCl(2)(NH(3))(2)] (cis-DDP).
Main Methods:
- High-Performance Liquid Chromatography (HPLC) for reaction monitoring.
- 2D [(1)H,(15)N] HMQC NMR spectroscopy for structural analysis of adducts.
- Study of reactions with various single-stranded and double-stranded DNA sequences.
Main Results:
- Trans-EE rapidly reacts with single-stranded DNA, forming G-N7/monochloro adducts.
- Double-stranded DNA duplexes lacking terminal guanine residues were largely unreactive towards trans-EE.
- Trans-EE preferentially binds to solvent-exposed terminal guanine residues in duplex DNA containing accessible G sites.
- In contrast, cis-DDP exclusively binds to the central GG motif in a specific duplex DNA sequence.
Conclusions:
- The steric bulk of trans-EE significantly influences its DNA binding selectivity.
- Trans-EE exhibits distinct reactivity patterns compared to cis-DDP, primarily binding to accessible guanine sites.
- These findings provide insights into the structure-activity relationships of platinum-based anticancer agents.