Proton magnetic resonance studies on short duplexes. II. The self-complementary oligoribonucleotide CpApUpG

Abstract

Proton nuclear magnetic resonance was used to examine double helix formation in the self-complementary oligoribonucleotide CAUG in neutral D2O containing 1.0 M NaCl. Using the procedure of incremental assignment all the nonexchangeable base and ribose anomeric protons could be assigned and were observed over the temperature range of 70 to 4 °C. The chemical shift changes that occurred over this temperature range were sigmoidal in nature which is indicative of base-pairing. From the plot of chemical shift vs. temperature a Tm of 24 ± 1 °C was determined. This is the first nmr study of a duplex formed from tetranucleotides which contains two internal A•U base pairs.