Nuclear magnetic resonance study of synthetic polynucleotides and transfer RNA

High resolution proton spectra in D 2 O solutions have been measured as functions of temperature for the following polynucleotides: Poly A, Poly U, Poly A and Poly U, Poly I, Poly C, Poly I and Poly C, and Transfer UNA from E. coli (strain B), and from yeast. At denaturation, peaks characteristic of the mononucleotide protons appear. Areas under the peaks can be used as a direct measure of denaturation. The sharpness of the spectral lines indicates that in the denatured form internal rotation about the ribose‐phosphate and the ribose‐base links is relatively free. Linewidths also show that monomer units remain in either the ordered or freely rotating state for at least 10 −4 sec.