ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Interaction of poly(X) with poly(U) to form a regular, ordered structure has been investigated by uv, CD, and ir spectroscopy. The XU complex exhibits a marked dependence of Tm on the nature of the alkali metal ion present in solution. Stability of the complex is surprisingly high and increases with ionization of X residues at N3. The ir evidence shows the U residues are present as the diketo form and X residues as the 6-keto-2-enolate anion and indicates that the X and U carbonyl groups are vibrationally coupled. A mixing curve exhibits a single minimum, at 1:1, but we conclude that the actual combining ratio is twice this value and that the formula of the complex is X2U2. We propose a model based on a four-standard helix with size-specific alkali metal complexing to X and U carbonyl oxygens in the axial channel of the helix. This model and previously suggested two-stranded structures are evaluated in terms of the physical and chemical properties of the complex.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360220903
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