The A--B transition: temperature and base composition effects on hydration of DNA |
| |
Authors: | Albiser G Lamiri A Premilat S |
| |
Institution: | Laboratoire de Biophysique Moleculaire, UMR 7565 Universite H. Poincare, Faculte des Sciences, BP 239, 54506, Vandoeuvre les Nancy, France. |
| |
Abstract: | Natural DNAs and some polynucleotides organised in fiber present the A--B form transition at a relative humidity (r.h.) which depends on the temperature. A shift of the midpoint of that helix--helix transition to higher r.h. values is observed when the temperature is risen. It is shown that the average number of water molecules associated to a nucleotide pair is the relevant parameter for the A-B transition and that this parameter can be given a precise value by a combination of different r.h. and temperature values. The minimum number of water molecules necessary to get the B form depends on the base composition of the DNA. It is observed that AT base pairs have a higher affinity toward water molecules than GC base pairs. In the B form there are 27 water molecules per GC nucleotide pair and 44 per AT pair. Moreover, we noted that the fraction of nucleotides in the B form as a function of the average number of water molecules associated per base pair does not depend on the temperature. The A helical form is obtained with about 11 water molecules per nucleotide pair and this number is not very sensitive to the base composition of DNA. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|