Abstract
A series of oligonucleotides of different sequences have been cloned to study DNA curvature. Several DNA fragments containing these oligonucleotides in various numbers of repeats were analyzed in 10% polyacrylamide gels. A strong gel migration anomaly was found for dA 4 sequences; a comparably very small but clearly detectable anomaly was observed for dA 3 (both in a repeat length of 10 base-pairs). The temperature and salt (NaCl, MgCl 2 ) dependence of the gel migration anomaly of these DNA fragments was measured. While a similar behaviour of all sequences is observed for the addition of NaCl, the temperature and MgCl 2 dependence of the anomaly varies with the oligonucleotide sequence. These data are interpreted in terms of local DNA structure changes induced by changes in the temperature and the MgCl 2 concentration which affect the planarity of the curved DNA fragments.