title: Understanding noncovalent interactions: ligand binding energy and catalytic efficiency from ligand-induced reductions in motion within receptors and enzymes.
abstract: Noncovalent interactions are sometimes treated as additive and this enables useful average binding energies for common interactions in aqueous solution to be derived. However, the additive approach is often not applicable, since noncovalent interactions are often either mutually reinforcing (positively cooperative) or mutually weakening (negatively cooperative). Ligand binding energy is derived (positively cooperative binding) when a ligand reduces motion within a receptor. Similarly, transition-state binding energy is derived in enzyme-catalyzed reactions when the substrate transition state reduces the motions within an enzyme. Ligands and substrates can in this way improve their affinities for these proteins. The further organization occurs with a benefit in bonding (enthalpy) and a limitation in dynamics (cost in entropy), but does not demand the making of new noncovalent interactions, simply the strengthening of existing ones. Negative cooperativity induces converse effects: less efficient packing, a cost in enthalpy, and a benefit in entropy.
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK. dhw1@cam.ac.uk
authors.forename: Dudley H
authors.initials: DH
authors.lastname: Williams
authors.forename: Elaine
authors.initials: E
authors.lastname: Stephens
authors.forename: Dominic P
authors.initials: DP
authors.lastname: O'Brien
authors.forename: Min
authors.initials: M
authors.lastname: Zhou
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D019277:Entropy; D004798:Enzymes / Q000737:chemistry* / Q000378:metabolism*; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D004798:Enzymes; D008024:Ligands; D011956:Receptors, Cell Surface