Binding of Foreign Molecules

The binding of foreign molecules or ions to DNA is liable to affect the helix conformation and its replication behaviour. This may be especially important in connection with drug action (Chapter 12.13). 

The principal types of binding which have been established are 

A special case of groove binding occurs when the foreign molecule is a suitable polynucleotide chain. In this instance, the bases share in the inter-base H bond system, and a local triple helix is 

FIGURE 11.43 Binding of foreign molecules to DNA. (a) Electrostatic, (b) grove and (c) intercalation. 

Porphyrins intercalate with DNA and can cause unwinding, and increase in viscosity and melting point. This behaviour is influenced by substituent groups and the nature of the central metal atom [32]. 

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