Relative binding responses for Z domain variants to mouse IgG1.

Solutions of Z domain variants (2 µM concentration) obtained after single amino acid substitutions at the seven targeted positions (K4, F5, Q9, Q10, F13, H18 and K35) were injected over a sensor chip surface containing immobilized mIgG1 monoclonal antibody protein and the equilibrium responses (plateau values) were recorded and normalized to the response values obtained for the wild type Z domain (WT) A blank surface (activated/deactivated) was used as negative control and used for buffer effect subtraction. (A) A representative overlay sensorgram from injections of ZWT, ZF5R and ZF5I variants over mIgG1 monoclonal protein showing higher equilibrium response values for the two mutant variants than for the ZWT domain. The response obtained from buffer injection only is also indicated (BUFFER). (B) Results from the analysis of the different variants. The horizontal line in each panel corresponds to the normalized response obtained for the wild type Z domain ( = 100).