Editing Allosteric regulation (section)

== Synthetic allosteric systems ==
There are many synthetic compounds containing several [[noncovalent]] binding sites, which exhibit conformational changes upon occupation of one site. Cooperativity between single binding contributions in such [[supramolecular]] systems is positive if occupation of one binding site enhances the affinity Δ''G'' at a second site, and negative if the affinity isn't highered. Most synthetic allosteric complexes rely on conformational reorganization upon the binding of one effector ligand which then leads to either enhanced or weakened association of second ligand at another binding site.<ref>{{cite journal | vauthors = Takeuchi M, Ikeda M, Sugasaki A, Shinkai S | title = Molecular design of artificial molecular and ion recognition systems with allosteric guest responses | journal = Accounts of Chemical Research | volume = 34 | issue = 11 | pages = 865–73 | date = November 2001 | pmid = 11714258 | doi = 10.1021/ar0000410 }}</ref><ref>{{cite journal | vauthors = Kremer C, Lützen A | title = Artificial allosteric receptors | journal = Chemistry: A European Journal | volume = 19 | issue = 20 | pages = 6162–96 | date = May 2013 | pmid = 23463705 | doi = 10.1002/chem.201203814 }}</ref><ref>{{cite journal | vauthors = Kovbasyuk L, Krämer R | title = Allosteric supramolecular receptors and catalysts | journal = Chemical Reviews | volume = 104 | issue = 6 | pages = 3161–87 | date = June 2004 | pmid = 15186190 | doi = 10.1021/cr030673a }}</ref> Conformational coupling between several binding sites is in artificial systems usually much larger than in proteins with their usually larger flexibility. The parameter which determines the efficiency (as measured by the ratio of equilibrium constants Krel = KA(E)/KA in presence and absence of an effector E ) is the conformational energy needed to adopt a closed or strained conformation for the binding of a ligand A.<ref>{{cite journal | vauthors = Schneider HJ | title = Efficiency parameters in artificial allosteric systems | journal = Organic & Biomolecular Chemistry | volume = 14 | issue = 34 | pages = 7994–8001 | date = September 2016 | pmid = 27431438 | doi = 10.1039/c6ob01303a }}</ref>

In many multivalent [[supramolecular]] systems<ref>{{cite journal | vauthors = Badjić JD, Nelson A, Cantrill SJ, Turnbull WB, Stoddart JF | title = Multivalency and cooperativity in supramolecular chemistry | journal = Accounts of Chemical Research | volume = 38 | issue = 9 | pages = 723–32 | date = September 2005 | pmid = 16171315 | doi = 10.1021/ar040223k }}</ref> direct interaction between bound ligands can occur, which can lead to large cooperativities. Most common is such a direct interaction between ions in receptors for ion-pairs.<ref>{{cite journal | vauthors = Kim SK, Sessler JL | title = Ion pair receptors | journal = Chemical Society Reviews | volume = 39 | issue = 10 | pages = 3784–809 | date = October 2010 | pmid = 20737073 | doi = 10.1039/c002694h | pmc = 3016456 }}</ref><ref>{{cite journal | vauthors = McConnell AJ, Beer PD | title = Heteroditopic receptors for ion-pair recognition | journal = Angewandte Chemie | volume = 51 | issue = 21 | pages = 5052–61 | date = May 2012 | pmid = 22419667 | doi = 10.1002/anie.201107244 }}</ref> This cooperativity is often also referred to as allostery, even though conformational changes here are not necessarily triggering binding events.