Aptamers-target crosslinks

The effect of the substitution of a guanine base by the oxidative lesion 8-oxo-7,8-dihydroguanine (OG) on the affinity of the DNA aptamer selected against L-argininamide (L-Rm) was studied by fluorescence anisotropy. Results shown that, depending on the OG position, the substitution either reduces, does not affect or increases the affinity. Specific oxidation of the OG-containing aptamers by an Ir(IV) salt was carried out to promote crosslinks formation with the L-Rm target. Results shown that crosslinks occur with the OG-containing aptamers but also with scramble sequences not supposed to bind L-Rm. Efforts to reduce formation of such unspecific crosslinks were only partially successful, as they failed to demonstrate that part of these adducts originated from specific recognition of aptamers towards L-Rm.