Interaction of DNA with heavy metal ions and polybases: Cooperative phenomena

✍ Scribed by I. R. Miller; D. Bach

• Publisher: Wiley (John Wiley & Sons)
• Year: 1968
• Tongue: English
• Weight: 584 KB
• Volume: 6
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1968.360060202

✦ Synopsis

The polarographically determined binding constants of Cu++ and Cd++ to DNA were found to decrease with the degree of binding. The binding causes a reduction in the electrostatic potential $ on the DNA molecule. The binding constant conforms to the relation K = KO exp ( -z e $ / k T ) . The binding constant at zero potential K O depends on the nature of the competing counterions to the phosphate group of the DNA; it is apparently smaller when Na+ rather than the ethylpyridonium residue of polyvinylpyridine serves as the competing coiinterion. The specific interaction between the ethylpyridonium residues of the polybase and the DNA is very weak, even though the polyelectrolytic interaction induced by the decrease of the electrostatic free energy is spectacular. The intereaction is reversible and equilibrium is maintained between the different interaction products. A reehuffling of the interacting partners can be effected by spontaneous or induced (by centrifugal forces) precipitation of the least soluble interaction products participating in the equilibrium.