Resolution Method of Two Sets of Binding Sites for the Cationic Surfactant–Urease Interaction

The binding of a homologous series of cationic surfactants with jack-bean urease has been studied by equilibrium dialysis at pH = 10 and 27 °C. The unusual concavity of a Scatchard plot has been interpreted by using the binding capacity concept. The relation between the binding capacity and the criterion of cooperativity (Hill coefficient) was obtained, and in the base of this relation a new method has been introduced for the resolution and characterization of two sets of binding sites in these systems, which is supported by microcalorimetric and spectroscopic data.