Biophysical characterization of VEGF-aHt DNA aptamer interactions

The binding of the well-studied DNA aptamer aHt (5′-ATACCAGTCTATTCAATTGGGCCCGTCCGTAT GGTGGGTGTGCTGGCCAG-3′), which has been demonstrated to recognize human vascular endothelial growth factor (VEGF165) to recombinant VEGF was characterized using fluorescence anisotropy, isothermal titration calorimetry and analytical ultracentrifugation. The negatively-charged DNA aptamer is selective for VEGF and does not recognize positively-charged hen egg lysozyme, or bovine serum albumin. In contrast to the VEGF association of the previously-described aV DNA aptamer, where the binding is enthalpically driven and sequence-specific, the binding of the aHt aptamer to VEGF is entropically-driven and not abolished by scrambling of the sequence.