Sequence and structure in double-stranded ribonucleic acid: (A-G-C-U)2 and (A-C-G-U)2

Edward Bubienko, Mary Alice Uniack, Philip N. Borer

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Abstract

Comparative studies of the thermally induced helix-coil transition in ribosyl (A-G-C-U)2 and (A-C-G-U)2 are described. Ordered structures form at low temperatures where the ribofuranose rings adopt the 3′-endo conformation and both oligomer helices have base-paired stacking arrangements qualitatively similar to the A-RNA family configuration. Especially for (A-C-G-U)2, there is a lack of quantitative agreement between the A-family base overlap and the 1H NMR data; ring-current and atomic diamagnetic anisotropies using A-form structures fail to predict five of the seven aromatic C-H resonances within 0.2 ppm. The NMR results are in better agreement with the A form for (A-G-C-U)2. For both oligomers, the changes in chemical shift for the anomeric (H1′) resonances indicate substantial (≥20°) changes in the average glycosidic torsion angle upon base pairing and stacking for the adenosine and cytidine residues; this angle in uridine and guanosine residues must change only slightly.

Original languageEnglish (US)
Pages (from-to)6987-6994
Number of pages8
JournalBiochemistry
Volume20
Issue number24
StatePublished - 1981

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ASJC Scopus subject areas

  • Biochemistry

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Bubienko, E., Uniack, M. A., & Borer, P. N. (1981). Sequence and structure in double-stranded ribonucleic acid: (A-G-C-U)2 and (A-C-G-U)2. Biochemistry, 20(24), 6987-6994.