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On the interaction between [Ru(NH3)6]3+ and the G-quadruplex forming thrombin binding aptamer sequence

par De Rache, Aurore ;Doneux, Thomas ;Kejnovská, Iva;Buess Herman, Claudine
Référence Journal of inorganic biochemistry, 126, page (84-90)
Publication Publié, 2013

Article révisé par les pairs

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Résumé :

The interaction between the thrombin binding aptamer (TBA), a G-quadruplex forming DNA sequence, andthe electroactive hexaammineruthenium(III) cation has been studied by electrochemical methods and circulardichroism spectroscopy. When TBA is immobilised on a gold surface in a typical aptasensor configuration,the [Ru(NH3)6]3+ cation can be bound to the electrode surface through its interaction with the TBA sequence.This interaction is strong enough to enable the rutheniumcomplex to remain at the surface when the electrode isimmersed in an electrolyte free of [Ru(NH3)6]3+, meaning that the complex does not diffuse back into thesolution. A stoichiometry of 2 [Ru(NH3)6]3+ per TBA strand has been determined, indicating that the interactiondiffers from the conventional, non-specific electrostatic charge compensation, forwhich a 5 to 1 ratiowould be expected between the triply charged cation and the 15 bases sequence. It is shown that this interactiontakes place not only at the surface, but also when both TBA and hexaammineruthenium(III) aredissolved in solution. Under such conditions, a similar stoichiometry of 2 [Ru(NH3)6]3+ per TBA strandhas been evidenced by two independent methods, namely circular dichroism spectroscopy and differentialpulse voltammetry.