Methoxymethyl Threofuranosyl Thymidine (4′-MOM-TNA-T) at the T7 Position of the Thrombin-Binding Aptamer Boosts Anticoagulation Activity, Thermal Stability, and Nuclease Resistance

[Image: see text] The synthesis of 4′-methoxymethyl threofuranosyl (4′-MOM-TNA) thymidine and derived oligomers of the G-rich thrombin-binding aptameric (TBA) sequence is reported. The G-quadruplex stability, anticoagulation activity, and the enzymatic stability of these oligomers bearing the 2′-3′-phosphodiester backbone as single substitutions in the loop regions are studied. Amongst all the oligomers, TBA-7T bearing the 4′-MOM-TNA unit at the T7 position formed a quadruplex with the highest thermal stability. It also resulted in enhanced anticlotting activity that allowed a one-third reduction in the dose, relative to TBA. Further, TBA-7T exhibited enhanced nuclease resistance properties to both endo- and exonucleases.