Improving Thermodynamic Stability and Anticoagulant Activity of a Thrombin Binding Aptamer by Incorporation of 8-trifluoromethyl-2′-deoxyguanosine

In this study, we incorporated 8-trifluoromethyl-2'-deoxyguanosine ((F)G) into a thrombin binding aptamer (TBA ). Circular dichroism, nuclear magnetic resonance (NMR), electrophoresis, and prothrombin time (PT) assay were performed to investigate the structure, thermodynamic stability, biological stability, and anticoagulant activity of the (F)G-modified TBA sequences. We found that the replacement of (F)G into TBA sequences led to a remarkable improvement in the melting temperature up to 30 degrees C compared with the native sequence. The trifluoromethyl group allowed us to investigate the TBA G-quadruplex structure by F-19 NMR spectroscopy. Furthermore, PT assays showed that the modified sequences can significantly improve the anticoagulant activity in comparison with the native TBA. Finally, we demonstrated that the trifluoromethyl-modified TBA sequence could function as an anticoagulant reagent in live rats. Our results strongly suggested that (F)G is a powerful nucleoside derivative to increase the thermodynamic stability and anticoagulant activity of TBA.