Skip to main content
. Author manuscript; available in PMC: 2012 Jul 19.
Published in final edited form as: Biochemistry. 2011 Jun 22;50(28):6157–6169. doi: 10.1021/bi2004558

Figure 2.

Figure 2

Scheme representing the two mechanisms of protein conformational change coupled to ligand binding. In the conformational-selection mechanism (red line) the apo form of the protein (unoccupied-open, UO) adapts to a certain probability a closed conformation (UC) to which the ligand binds and stabilizes the conformation (bound-closed, BC). In the induced-fit mechanism (green line) the ligand binds to the apo conformation of the protein (BO). This binding event triggers the conformational change to the final BC state. The top curve shows a model of the free energy of the unbound form of the protein as a function of an arbitrary reaction coordinate describing the conformational change between open and closed form; the bottom curve displays the associated model of the free energy of the bound form.