Proton magnetic resonance studies at 220 MHz of alanine transfer RNA

Proton magnetic resonance spectra at 220 MHz of alanine transfer RNA do not permit assignments of individual peaks due to each of the common bases; only a peak attributable to protons at position eight in adenine can be assigned with certainty. Measurements of the relative areas of proton magnetic resonance peaks due to the base and ribose-1′ protons indicate that the ribose moieties of tRNA are not involved in bonds stronger than those experienced by the bases. Proton magnetic resonance peaks attributable to the methyl and dihydro protons of the rare bases can be distinguished in the 220 MHz spectra; the variation of their line widths and chemical shifts with increasing temperature indicates that the rare bases are located in regions of the alanine transfer RNA molecule which are more highly organized than indicated by an open cloverleaf model.