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

Abstract

synopsisThe interaction of unsubstituted purine with polyuridylic acid in DzO solution a t neutral pD has been studied by high resolution proton magnetic resonance spectroscopy. The poly U proton resonances were shifted to higher fields by the added purine, indicating that purine binds to the uracil bases of the polymer by base stacking. Severe broadening of the purine proton resonances was also observed, providing strong evidence for the intercalation of purine between adjacent uracil bases of the polymer. The line widths of the poly U proton resonances were not noticeably broadened in the presence of purine; thus, the binding of purine to poly U does not result in a more rigid or ordered structure for the polymer.

Homoconjugate addition of organocopper reagents to cyclopropanes and its application to the synthesis of prostanoids

“…The polymer was in a random coil form and rapid segmental motion leading to long relaxation times yielded sharp lines. 6 In both cases an increase in the intensity of the signal was observed as predicted by theory.3…”

Studies of the conformation and interaction in dinucleoside mono- and diphosphates by proton magnetic resonance

“…Similar results are obtained at 60 and 28°. The/ni'~h-2> of uridine (0.10 m) was found also to be decreased from about 4.5-4.1 cps in the presence of 0.11 m purine (Bangerter and Chan, 1968). Therefore, in this case, the extent of reduction of /h-1'-h-2' value does not correspond directly to the extent of shielding of the H-l' proton (or the base as well) by the influence of the neighboring molecule in the stacks through the ringcurrent effect.…”

Bases, Nucleosides, and Nucleotides

“…More recently, this problem was reinvestigated by Chan and co-workers by the PMR technique [260,261]. First, they studied the PMR spectra of purine (H-2, H-6, and H-8) and of TpT, TpdU, and dUpT (T = thymine, dU = 2'deoxyuridine) in D 2 0 solution influenced by each other [260].…”

“…Upon the addition of purine, the resonance of the base protons and (Н-Г) protons of the dimers shifted upfield significantly. Later on, Bangerter and Chan extended their investigation to the binding of purine to poly U [261]. Binding of purine to the dimers also induces broadening of the linewidth of the purine molecule, especially the H-6 protons.…”