Binding of a bolton-hunter substituted homostatine analog to affinity-immobilized human renin

Abstract The binding of a Bolton-Hunter reagent substituted homostatine analog, SDZ 213–776, to human renin was investigated at pH 6.5 and 7.4. At both pH values, SDZ 213–776 bound to human renin in a reversible and saturable manner. The binding characteristics conformed to a one-site binding model. The dissociation constant K d , obtained at equilibrium, was four-fold lower at pH 6.5 that at pH 7.4 (0.94 nM vs 3.7 nM). Under non-equilibrium conditions, only the association kinetic constant k +1 , was affected by pH. The results of the binding assay at pH 6.5 correlated well with those obtained in enzymatic assay at the same pH.