Allosteric binding site ligands

Allosteric binding occurs when two molecules bind to different sites on the target. When the two molecules are identical, it is termed homotropic interaction. If the molecules differ from each other, it is termed heterotropic interaction. Binding is competitive when two different ligand molecules compete for the same site. We discuss ligand binding further in Chapter 3. The specificity of ligand-receptor interaction is illustrated in Exhibit 2.9. 

Many natural compounds and drugs do not directly activate or inhibit a receptor process rather they bind to allosteric sites on the receptor protein to modulate the effects of the endogenous ligand. Examples of... 

It was pointed out in Section 6.8 that the term allosteric as coined by MCJ and MWC has been used with three different meanings. In Chapter 6 we discussed the allosteric effect in hemoglobin (Hb). There, the two allosteric sites were identical this has been referred to as the homotropic effect. When the two sites bind different ligands, the heterotropic effect, the induced fit by one ligand can either enhance or diminish the binding affinity of the second ligand (see the example in Section 4.5). 

D. A. Annis, N. Nazef, C.-C. Chuang, M. P. Scott, H. M. Nash A general technique to rank protein—ligand binding affinities and determine allosteric versus direct binding site competition in compound mixtures. 

Scott MP, Nash HM A general technique to rank protein-ligand binding affinities and determine allosteric versus direct binding site... 

---