Figure 2: Binding affinity of hnRNP A2 for the LTR-II + III + IV G4 and mutant sequences measured by surface plasmon resonance (SPR) analysis.

The human recombinant hnRNP A2 was immobilized on the SPR chip by amine coupling chemistry and the unlabelled oligonucleotides were bound at a flow rate of 25 μl/min, with contact time and dissociation time of 120 s in HEPES-KCl buffer. Sensograms were obtained in the oligonucleotide concentration range of 31.25 nM–2 μM. SPR sensograms of (a) LTR-II + III + IV with ka 4.7 × 104 ± 5.2 × 102 Ms−1 and kd 9.2 × 10−4 ± 7.5 × 10−5 s−1, (b) LTR-II + III + IV M4-5 with ka 2.8 × 104 ± 3.4 × 102 Ms−1 and kd 10.0 × 10−4 ± 8.4 × 10−5 s−1 and (c) LTR-II + III + IV Random, the ka and kd values of which are not reliably measurable. Sensograms are shown as grey lines and their respective fits as black lines.