Ligand induced fit

Koshland. Induced fit suggested for protein-ligand interactions. 

The second generalization, developed mainly by Koshland, is based on the recognition that enzymes (like any protein) have a multitude of conformations at equilibrium. Since the ligand is likely to interact differently with the various conformations, one can expect a shift in the distribution of conformations induced by the binding process. This is the induced fit model. It states that the best fit (by either geometrical or by a complementary pattern) does not necessarily exist before... 

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). 

Figure 8.2. Induced fit model. The ligand L approaching the site on P will cause a change in P so that the fit between L and P improves.

A model used to explain cooperativity on the basis of ligand-induced changes in conformation that may or may not alter the subunit-subunit interfaces of oligomeric enzymes and receptors. This model has also been referred to as the Adair-Koshland-Nemethy-Filmer model (AKNF model), the induced-fit model, and the sequential model. 

The original concept offered to explain why enzymes exhibit such a high degree of substrate specificity. The active site of an enzyme was viewed as a topological template for a particular reactant hence, there is an enzyme-substrate complementarity . See Induced-Fit Model Ligand-Induced Conformational Change E. Fischer (1894) Ber. 27, 2985. 

INDUCED-FIT MODEL LIGAND-INDUCED CONFORMATIONAL CHANGE... 

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