Binding of HRG to DNA or RNA as determined using SPR. (A) Biotin DNA or (B) biotin RNA was adsorbed to 200 to 300 RU on separate flow cells containing immobilized streptavidin. An unmodified streptavidin-containing cell served as the reference control. After injecting 0 to 0.125 nM HRG into flow cells for 300 seconds to assess binding, buffer was injected for 800 seconds to assess dissociation. The amount of HRG bound at equilibrium (Req) was corrected for background and plotted vs input HRG concentrations. Data represent the mean ± SD of 3 determinations and were fit by nonlinear regression analysis using a rectangular hyperbola (line). Insets, representative binding sensorgrams for DNA and RNA, where input HRG concentrations are indicated adjacent to each tracing.