ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The double-stranded helical complexes of poly(dG-dC) and of poly(dG-m5dC) are shown to convert from B- to Z-DNA-type conformations at moderate or low ionic strengths, lower for the 5-methyl than for the non-methyl species, in a highly cooperative temperature-dependent equilibrium. In the presence of low concentrations of divalent ion, e.g., Mg2+, the temperature at which the B → Z transition occurs is virtually independent of the salt concentration and the B-conformation is favored at lower temperature, while the Z-conformation is favored at higher temperature. Since the Debye-Hückel screening parameter changes rapidly with ionic strength in this region, electrostatic interaction with the free ions appears to be only a small factor in the forces that promote the transition; the temperature dependence must derive principally from effects on the solvent. The temperature dependence at high salt concentrations is also reported.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360240202
