Nucleic Acids Research, 1977, Vol. 4, No. 5 1633-1648
© 1977
Articles |
1H NMR studies of transfer RNA III: the observed and the computed spectra of the hydrogen-bonded NH resonances of baker's yeast transfer-RNAPhe1
The Division of Biophysics, School of Hygiene and Public Health, The Johns Hopkins University Baltimore, MD 21205, USA
Received February 4, 1977.
The hydrogen-bonded NH resonances of Baker's yeast tRNAPhe in H20 solution with Mg++ have been measured by a 360 MHz spectrometer at 23°C. Totally, fifteen peaks and one shoulder can be resolved which represent 25±1 protons. Based on the refined atomic coordinates of the tRNAPhe in the or-thorhombic crystal, on the recent advances in the distance dependence of the ring-current magnetic field effects2 and on the adopted values for the isolated hydrogen-bonded NH resonances, a computed spectrum consisting of 23 protons was constructed. A quantitative comparison by computer was made between the computed spectrum and the spectrum simulated from the observed spectrum. These two spectra are closely similar but not identical. We suggest that the conformation of yeast tRNAPhe in aqueous solution is closely similar but not identical to that found in the crystal, especially in the T
C region and D region. Also the NH resonances in 3–4 proposed hydrogen bonds (most likely for tertiary structure) may exchange very rapidly in aqueous solution.