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Phosphorus-31 nuclear magnetic resonance of double- and triple-helical nucleic acids. Phosphorus-31 chemical shifts as a probe of phosphorus-oxygen ester bond torsional angles

Journal Article · · Biochemistry; (United States)
OSTI ID:5548042

The temperature dependence to the /sup 31/P NMR spectra of poly(d(GC))-poly(d(GC)), d(GC)/sub 4/, phenylalanine tRNA (yeast) and mixtures of poly(A) + oligo(U) is presented. The /sup 31/P NMR spectra of mixtures of complementary RNA and of the poly d(GC) self-complementary DNA provide torsional information on the phosphate ester conformation in the double, triple, and ''Z'' helix. The increasing downfield shift with temperature for the single-strand nucleic acids provides a measure of the change in the phosphate ester conformation in the single helix to coil conversion. A seperate upfield peak (20-26% of the total phosphates) is observed at lower temperatures in the oligo(U)-poly(A) mixtures which is assigned to the double helix/triple helix. Proton NMR and UV spectra confirm the presence of the multistrand forms. The /sup 31/P chemical shift for the double helix/triple helix is 0.2-0.5 ppm upfield from the chemical shift for the single helix which in turn is 1.0 ppm upfield from the chemical shift for the random coil conformation.

Research Organization:
Univ. of Illinois, Chicago
OSTI ID:
5548042
Journal Information:
Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 21:3; ISSN BICHA
Country of Publication:
United States
Language:
English