The Monod-Wyman-Changeux model is used to describe the saturation of hemoglobin with oxygen. Accounts for homotropic cooperative effects on each of the four binding sites.
The Monod-Wyman-Changeux model was first used to describe indirect interactions of neighboring binding sites (each protomer of a protein has exactly one binding site) on each other (allosteric effect). It uses a simple model where the protein (Hemoglobin) can be found in one of at least two different, reversible, conformational states. The affinity for the ligand (O2) is different for the two conformational states. If a ligand binding to one site causes a confomational change of the protomer then the conformational change occurs for all protomers (binding sites). This model describes homotropic cooperative effects between binding sites but does not take into account heterotropic effects due to different allosteric ligands (ex: 3 ligands where one is an inhibitor and one is an activator for the third ligand). See Notes page for additional information.
The equations for this model may be viewed by running the JSim model applet and clicking on the Source tab at the bottom left of JSim's Run Time graphical user interface. The equations are written in JSim's Mathematical Modeling Language (MML). See the Introduction to MML and the MML Reference Manual. Additional documentation for MML can be found by using the search option at the Physiome home page.
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Monod J, Wyman J, Changeux J: On the Nature of Allosteric Transitions: A Plausible Model Journal of Molecular Biology, 12:88-118, 1965
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Model development and archiving support at https://www.imagwiki.nibib.nih.gov/physiome provided by the following grants: NIH U01HL122199 Analyzing the Cardiac Power Grid, 09/15/2015 - 05/31/2020, NIH/NIBIB BE08407 Software Integration, JSim and SBW 6/1/09-5/31/13; NIH/NHLBI T15 HL88516-01 Modeling for Heart, Lung and Blood: From Cell to Organ, 4/1/07-3/31/11; NSF BES-0506477 Adaptive Multi-Scale Model Simulation, 8/15/05-7/31/08; NIH/NHLBI R01 HL073598 Core 3: 3D Imaging and Computer Modeling of the Respiratory Tract, 9/1/04-8/31/09; as well as prior support from NIH/NCRR P41 RR01243 Simulation Resource in Circulatory Mass Transport and Exchange, 12/1/1980-11/30/01 and NIH/NIBIB R01 EB001973 JSim: A Simulation Analysis Platform, 3/1/02-2/28/07.