Rate constants and activation parameters for the mobility of bulk and DNA-associated glycol–water solvents
✍ Scribed by John G. Milton; William C. Galley
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1986
- Tongue
- English
- Weight
- 687 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0006-3525
No coin nor oath required. For personal study only.
✦ Synopsis
The decrease in mobility of viscous glycol-water solvents when associated with native DNA is quantified from a study of the loss of the exciting-wavelength dependence of the phosphorescence spectrum of free and bound proflavin with increasing temperature. The data are interpreted in terms of a distribution of rate constants with an Arrhenius temperature dependence. Over the temperature range of the experiments a relative decrease of -lo4 in the average rate constant is observed for reorientation of the solvent when associated with DNA. The basis for this large reduction is found to derive from a large decrease in the pre-exponential factors (i.e., activation entropy) associated with the reorientation rate constants. The changes in the distribution of rate constants and the activation parameters for solvent mobility induced by DNA do not resemble the changes observed for any one of a number of small ion or molecule perturbations. The results suggest the presence of disorganized, relatively immobile solvent in association with DNA.