NMR titration of 5/B/6 MBL with the 10-mer aptamer reveals the site of aptamer binding.

A) 2D 1H-15N HSQC spectra of lysine residues that showed chemical shift perturbation upon the addition of 10-mer. The direction of the movement for each peak is shown with a black arrow. The lightest color represents the no inhibitor condition and the darkest color represents presence of 3 mM of the 10-mer (i.e., 4.0 molar equivalents). B) Binding curves for the three lysine residues. The calculated KDs from individual fits of the Lys78, Lys104, and Lys107 chemical shift change are 125 ± 4 nM, 233 ± 6 nM, and 100 ± 3 nM, respectively. Errors in the KD are from the fit.