BRAINCAKEHow Cisplatin Prevents DNA Replication
Cisplatin kills cancer cells by binding to their DNA and stopping it from being copied.
Blood plasma has a high chloride ion concentration, so cisplatin stays as [Pt(NH3)2Cl2] while it is carried round the body. Inside cells the chloride concentration is much lower, so a chloride ligand can be replaced by a water molecule, making the complex more reactive.
The platinum then bonds to DNA in a ligand substitution reaction. A nitrogen atom on a guanine base has a lone pair and acts as a ligand: it forms a co-ordinate bond to Pt, displacing a chloride (or water) ligand. The second leaving ligand is then replaced by a nitrogen atom on a second guanine, usually the neighbouring guanine on the same strand. The two NH3 ligands stay bonded to the platinum.
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More in Amino Acids, Proteins and DNA
- Secondary Structure of Proteins
- Tertiary Structure of Proteins
- Enzymes and Stereospecific Active Sites
- Drug Action and Enzyme Inhibitors
- Structure of DNA Nucleotides
- Hydrogen Bonding between DNA Bases
- Cisplatin
- Side Effects of Cisplatin
All 15 lessons in Amino Acids, Proteins and DNA · All AQA A-level Chemistry topics