SPR interaction analyses regarding the affinity of aptamer PA#2/8.

<p>Biacore X100 / sensor chip CAP / ligand: 3'-biotinylated aptamer PA#2/8 with immobilization levels of 1086 RU (A), 1158 RU (C), 506 RU (E), 316 RU (F) / analyte: recombinant and native Protein A with different concentrations (10–5000 nM, 1000 nM in triplicate) / single-cycle mode (H) with an aptamer level of 516 RU and sequential injections of five ascending concentrations of recombinant Protein A (62, 185, 556, 1667, 5000 nM) as triplicate. Double-referenced sensorgrams are shown (reference surface modified with unselected SELEX library, buffer injection). Black lines represent the fit to bivalent analyte binding model. The corresponding plots (B, D, G, I) of steady-state binding from the end of the association phases against analyte concentration were used to calculate the steady-state affinity.