dC-dG Alternating Oligonucleotides: Thermodynamic and Kinetic Aspects of the B-Z Transformation |
| |
| Authors: | Giorgio Manzini Luigi E. Xodo Franco Quadrifoglio Jacques H. van Boom Gijsbert A. van der Marel |
| |
| Affiliation: | 1. Dept. of Biochemistry, Biophysics and Macromolecular Chemistry , University of Trieste , I-34127 , Trieste , Italy;2. Gorlaeus Laboratory , State University , P.O.Box 9502, 2300 , RA Leiden , The Netherlands |
| |
| Abstract: | Abstract The alternating cytosine-guanine oligodeoxyribonucleotides (dCdG)n, (dGdC)n, (dCdG)n, (dCdG)ndC (n=3,4), (dGdC)7 and dG(dCdG)3 have been studied by UV and CD spectroscopy at different temperatures and NaCl concentrations. The analysis of the melting data, assuming an all-or-none model, reveals that in the B-conformation the 5′G/C3′ stacking interactions are enthalpically favoured with respect to the 5′C/G3′ one. The CD investigation of the B-Z equilibrium shows that the Z-conformation is enthalpically stabilized, while the B-conformation is entropically favoured, in the range of NaCl concentration considered (1 to 5M). The kinetic data for the B-Z transformation, obtained with a salt-jump technique for the hexamer (dCdG)3, support a mechanism by which (he Watson-Crick hydrogen bonds are broken before the bases flip over separately and eventually stack, reforming the H-bonds, in the new helix. |
| |
| Keywords: | Acetylchloinesterase Withanolide A Docking Simulations Withania |
|
|
