FIG. 5.
Stable binding of NC to pentanucleotides. SPR chips were prepared with streptavidin alone (A), or with 11.4 RU of (TG)4 (B), 9.8 RU of TGTGT (C), or 16.8 RU of GTGTG (D). These chips contained 0, 0.08, 0.2, and 0.11 mol of oligonucleotide per mol of streptavidin, respectively. The chips were then tested with 10, 25, 50, 100, 200, and 400 nM NC solutions (A and B) or with 10, 25, 50, 200, and 400 nM NC solutions (C and D). (Because of the extremely low levels of oligonucleotide on the chips in this experiment, a relatively large amount of NC bound in the nonsaturable mode. Thus, as noted in the Discussion section, the amplitude of binding during the washon does not reflect the affinity or stoichiometry of the high-affinity, saturable mode of binding of NC to an oligonucleotide.