UV/Vis melting RNA samples (0.25-0.5 mM) were prepared in NMR buffer and the melting profiles measured between 275 K and 368 K using a Varian Bio 300 UV/Vis instrument equipped with a Cary Temperature Controller. The absorbance at 260 nm was recorded every 0.5 with a ramp rate of 0.5 /min. The two-state helix to coil melting transition was analyzed using