Recently, techniques that are sensistive to the dynamics of proteins, such as NMR spectroscopy and IR spectroscopy have challenged some of the core assumptions of the induced fit model. Specifically, enzymes such as EXAMPLES have been found to inhabit their "bound" conformations even in the absence of ligand (cite!). Additionally, some enzyme phenomena are not readily explained by the induced fit model (EXAMPLES). This has led to the proposal of a new theory of enzyme dynamics; conformational selection. In it, an enzyme is in equilibrium with multiple conformational states. Most of the enzyme may populate the ground state; however, certain sparsely-populated, higher energy conformations may be important for substrate binding and catalysis. When a substrate is present it stabilizes the enzyme in the bound conformation, causing more of the enzyme to populate this conformation. Enzyme dynamics may then be important for catalysis.
This eliminates the problem of having substrates "cause" a conformational change.
Conformational selection is important in macromolecular recognition,[1]
- ^ David D Boehr, Ruth Nussinov & Peter E Wright (2009). "The role of dynamic conformational ensembles in biomolecular recognition" (HTML). Nature Chemical Biology. 5: 789–796.
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