Editing Active site (section)

===Conformational selection hypothesis===
This model suggests that enzymes exist in a variety of conformations, only some of which are capable of binding to a substrate. When a substrate is bound to the protein, the equilibrium in the conformational ensemble shifts towards those able to bind [[ligand (biochemistry)|ligand]]s (as enzymes with bound substrates are removed from the equilibrium between the free conformations).<ref name="Copeland2013">{{Cite book| publisher = John Wiley & Sons, Ltd| isbn = 978-1-118-54039-8| pages = 287–344| last = Copeland| first = Robert A.| title = Evaluation of Enzyme Inhibitors in Drug Discovery| chapter = Drug–Target Residence Time| date = 2013}}</ref>