Lac repressor - lac operator interaction. Circular dichroism study

Abstract

The interaction between lac repressor and a small operator DNA fragment have been examined by circular dichroism spectroscopy. The binding of lac repressor on the operator induces a conformation change of the DNA which is different from that observed upon non specific binding on non operator DNA. The CD titration curve indicates that the stoechiometry of interaction is complex. A two operators-one repressor complex was found. This result was confirmed by a gel filtration experiment.