Phosphorus-31 nuclear magnetic resonance of highly oriented DNA fibers. 1. Static geometry of DNA double helices.
The static geometry of the phosphodiesters in oriented fibers of DNA and a variety of polynucleotides was investigated by solid-state 31P nuclear magnetic resonance (NMR) spectroscopy. The structural parameters of the phosphodiester backbone expressed by two Euler angles beta and gamma were estimated on the basis of the NMR spectra of natural DNA, poly(dA).poly(dT), poly(rA).poly(dT), and poly-(rA).poly(rU). The Euler angles were calculated by using the known single crystal structures of a decamer, r(GCG)d(TATACGC), and a dodecamer, d(CGCGAATTCGCG). The distribution pattern of the Euler angles was quite different between these two oligonucleotides due to the different types of conformation, and it was fully consistent with the 31P NMR results, showing that the conformation of the B form DNA is very heterogeneous while that of the A or A' form is much more invariable with regard to the base composition. The structural parameters were also calculated by using various structures determined by the X-ray fiber diffraction studies, and they were evaluated on the basis of the 31P NMR data. Notably, poly(dA).poly(dT) fibers exhibited abnormal 31P NMR spectra which were very broad in line width and were not appreciably perturbed by hydration; a coiled double-helical structure is proposed as the most plausible model for this polymer.
D000818:Animals; D004247:DNA; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008961:Models, Structural; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D009841:Oligonucleotides; D010758:Phosphorus; D011119:Polynucleotides; D012474:Salmon; D013094:Spermatozoa; D013329:Structure-Activity Relationship; D014961:X-Ray Diffraction
D009841:Oligonucleotides; D011119:Polynucleotides; D010758:Phosphorus; D004247:DNA