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Updated: Jul 13, 2026
13:26
Determination of Protein-ligand Interactions Using Differential Scanning Fluorimetry
Published on: September 13, 2014
Cooperative equilibrium curves generated by ordered ligand binding to multi-site molecules
1Université de Rennes1 UMR6026 CNRS IFR140 Campus de Beaulieu, 35042 Rennes cedex France. denis.michel@univ-rennes1.fr
Biophysical Chemistry
|July 24, 2007
Summary
Sigmoid binding curves, often indicating cooperativity, can also arise from ordered ligand binding to receptors with identical sites, not just allostery. This mechanism, based on mass action, may explain some cooperative effects in biological and non-biological systems.
Area of Science:
- Biochemistry
- Chemical Kinetics
- Molecular Biophysics
Background:
- Sigmoid equilibrium curves and Hill coefficients > 1 typically indicate cooperativity or homotropic allostery.
- This means ligand affinity increases with receptor saturation.
Purpose of the Study:
- To investigate alternative mechanisms generating sigmoid binding curves.
- To explore if ordered ligand binding can mimic allosteric cooperativity.
Main Methods:
- Mathematical transformation of the Adair scheme of equilibria.
- Analysis using the Hill plot.
Main Results:
- Sigmoid binding curves can be generated by ordered ligand binding to receptors with multiple, identical binding sites.
- This mechanism relies solely on the law of mass action.
Conclusions:
- Ordered ligand binding to identical sites can produce sigmoid curves, mimicking allosteric cooperativity.
- This mass action-based mechanism may contribute to cooperative effects in various systems, including heme proteins.
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