title: A new method of applying the Sips equation.
abstract: The Sips equation is frequently used in immunochemistry to describe the relationship between antibody-binding site concentration (n0[Ab]), antigen concentration, intrinsic affinity constant (K), and the heterogeneity index (a) of the affinity constant. Usually n0[Ab] is determined before calculating the remaining parameters (K and a). A new method is proposed which does not require knowledge of n0[Ab] nor an extensive calculation to determine K and a. The method can also be used to determine the antibody-binding site concentration without purified antibody or ligand saturation of the binding sites. This method can be applied to any antibody which binds a monovalent ligand and which can be obtained at a concentration greater than 1/K. Since the Sips equation can be applied to any ordinary chemical reaction by setting a=1, the proposed method can be used generally to determine the affinity constant and the initial concentration of one of the reactants.
mesh_terms: D000818:Animals; D000937:Antigen-Antibody Reactions; D000941:Antigens; D001666:Binding Sites, Antibody; D006168:Guinea Pigs; D007106:Immune Sera / Q000494:pharmacology; D007120:Immunochemistry / Q000379:methods; D010954:Plasmacytoma / Q000276:immunology; D011817:Rabbits; D014301:Trinitrobenzenes / Q000276:immunology
chemical_list: D000941:Antigens; D007106:Immune Sera; D014301:Trinitrobenzenes