title: Graphical analysis of competitive binding of comparable concentrations of ligand, inhibitor and protein. Ligand binding to serum albumin.
abstract: In contrast to analysis for competitive binding in enzyme kinetics, no linear plot for analysing competitive binding of two ligands to a protein, where the concentrations of the three reactants are comparable, seems to exist. In the present communication it is shown that in this situation a linear plot can be obtained by the use of the simple equation VA/VB = KA/KB X [Af]/[Bf], where VA and VB are the average number of moles of ligand A and ligand B bound per mole of protein, respectively; [Af] and [Bf] are the concentrations of free ligand A and free ligand B, respectively; and KA and KB are the corresponding association constants. The plot is commented on both theoretically and experimentally using ligand binding to human serum albumin as an example.
mesh_terms: D001665:Binding Sites; D001667:Binding, Competitive; D003975:Diazepam / Q000097:blood*; D006801:Humans; D007700:Kinetics; D008024:Ligands; D008433:Mathematics; D011485:Protein Binding; D012709:Serum Albumin / Q000378:metabolism*; D014364:Tryptophan / Q000097:blood*
chemical_list: D008024:Ligands; D012709:Serum Albumin; D014364:Tryptophan; D003975:Diazepam