Proton magnetic resonance studies on short duplexes. I. Helix formation by the duplex set GpApGpC:GpCpUpC

Abstract

Proton magnetic resonance bas been used to investigate the double stranded RNA helix GAGC:GCUC, whose sequence corresponds to the duplex neck region of several tRNAs, a possible aminoacyl-tRNA synthetase recognition site. The nonexchangeable base and ribose anomeric resonances of the separate tetranucleotides were characterized by linear and predominantly upfield chemical shift changes as the temperature was decreased from 65 to 15 °C. When these strands were mixed nonlinear, sigmoidal shift changes consistent with base pairing were observed. The melting temperature of the duplex was determined to be 42 ± 1 °C which was in excellent agreement with the value obtained from optical methods. This is the first 1Hmr study of a non-self-complementary duplex prepared from synthetic tetraribonucleotides.