Nuclear magnetic resonance study of synthetic polynucleotides and transfer RNA

Abstract

synopsisHigh resolution proton spectra in D20 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 RNA from E. co2i (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 a t least lo-' see.

Proton magnetic resonance study of the binding of purine to polyuridylic acid

“…The absence of such broad lines for poly U is taken to support a relatively disordered, random coil structure for the polymer under these conditions of temperature and ionic strength. 12 Resonances of the ribose HP, H3/, H4/, HSr, and H6u protons occur from about -440 to -520 cps, and are broad, poorly resolved bands due to extensive spin-spin coupling and magnetic dipolar broadening of the individual components. Little information could be obtained from this spectral region.…”

Nuclear magnetic resonance studies on the biochemistry of biopolymers

“…Earlier studies of several polynucleic acids suggest that these species exhibit an nmr absorption only when the polymer possesses a disordered structure. 137,138 Proton chemical shifts and line-width data have been used…”

A carbon‐13 magnetic resonance study of the helix–coil transition in polyuridylic acid

“…[13][14][15][16] At neutral pH and room temperature, the polymer exists as a random coi1, 16 with little or no stacking, as has been confirmed by 'H nmr spectroscopy. [17][18][19] Below a certain transition temperature T, however, there is a sudden decrease in ultraviolet absorption indicating the formation of an ordered structure.15 The experimental results suggest that below T,, poly(U) adopts a double-helical structure due to the folding of the molecule on itself leading to formation of multi-hairpins. At lower temperature such branches become longer and finally well below T , a single hairpin results.…”