Biomaterial Database

Scatchard plot and heterogeneity in binding affinity of labeled and unlabeled ligand. 1975

H J Hollemans, and R M Bertina

In saturation analysis the Scatchard plot is a generally accepted method for calculation of the affinity constant, K, and the molar concentration, q, of the binder. However, in a system where the K's for the labeled and unlabeled ligand are unequal, a nonlinear plot can be obtained from which incorrect values for K and q may be calculated. This paper mathematically explains how the plot may deviate and under which conditions there will be a maximum in the curve. When the binding sites are homogeneous, the coordinates of this maximum can be used to calculate K and q. A general mathematical expression is derived on the basis of which a linear curve can be constructed for calculation of q and K, which is valid even when affinity for the labeled and unlabeled ligand is not identical.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008024	Ligands	A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme. Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed)	Ligand
D008433	Mathematics	The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Mathematic
D008722	Methods	A series of steps taken in order to conduct research.	Techniques,Methodological Studies,Methodological Study,Procedures,Studies, Methodological,Study, Methodological,Method,Procedure,Technique
D008956	Models, Chemical	Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.	Chemical Models,Chemical Model,Model, Chemical
D011869	Radioligand Assay	Quantitative determination of receptor (binding) proteins in body fluids or tissue using radioactively labeled binding reagents (e.g., antibodies, intracellular receptors, plasma binders).	Protein-Binding Radioassay,Radioreceptor Assay,Assay, Radioligand,Assay, Radioreceptor,Assays, Radioligand,Assays, Radioreceptor,Protein Binding Radioassay,Protein-Binding Radioassays,Radioassay, Protein-Binding,Radioassays, Protein-Binding,Radioligand Assays,Radioreceptor Assays