Ultrafast dynamics show that the theophylline and 3-methylxanthine aptamers employ a conformational capture mechanism for binding their ligands

Ultrafast time-resolved fluorescence spectroscopic experiments were used to probe picosecond dynamics of the theophylline-binding RNA aptamer. Picosecond dynamics measured for the modified aptamer that binds with higher affinity to 3-methylxanthine than theophylline revealed that the modified aptamer exhibit less heterogeneity in the aptamer-3-methylxanthine complex than those observed in the theophylline aptamer-theophylline complex.