Physical Binding with, or Chemically Modifying, Natural Macromolecules

3 Physical Binding with, or Chemically Modifying, Natural Macromolecules 

Physical binding with, or chemically modifying, natural macromolecules such as DNA and RNA, can involve either direct interaction or the incorporation of synthetic analogues of structural components (e.g. one of the heterocyclic bases) into the polymer. 

Binding at the receptor may be competitive (i.e. the drug is in equilibrium/exchange with the natural agent) or it may be non-competitive - firmly bound with no exchange. 

Receptors usually exist as a number of sub-types, often with further sub-divisions, which mediate different physiological effects by interaction with the single natural agent. The key to a successful drug very often depends on devising a molecule that has a selective interaction with just one sub-type. 

Sometimes, binding at a site other than the normal receptor (allosteric binding) is the mechanism of action - the remote binding alters the shape of the protein as a whole and hence influences the receptor. Binding/action at the receptor is often only the start of a complex cascade of actions within the cell. 

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