https://doi.org/10.1351/goldbook.14112
Graphical representation of the relationship between the amount of ligand that is specifically bound to a receptor per mass of binding material and the amount of free ligand.
Notes:
- For a system containing a single binding site and lacking cooperative interactions, the binding isotherm is described by \[B = B_{\max}[\ce{L}]/(K_{\rm{d}} + [\ce{L}])\] where \(\ce{B}\) is the amount of ligand specifically bound, \([\ce{L}]\) is the amount concentration of free ligand, \(K_{\rm{d}}\) is the equilibrium dissociation constant of the ligand, and \(B_{\rm{max}}\) is the maximal specific binding of a ligand. The equation describes a hyperbola with \(B_{\rm{max}}\) as the asymptote. \(B_{\rm{max}}\) is defined quantitatively as the amount of ligand bound per mass of binding material, with units, e.g., \(\pu{pmol mg-1}\).
- A Scatchard plot was formerly used to determine \(B_{\rm{max}}\) and \(K_{\rm{d}}\). It is now more common to determine these parameters by nonlinear least-squares fitting to the binding equation given above.
- The total number of receptors or binding sites in the system is proportional to \(B_{\rm{max}}\).