FLUORESCENCE OF COMPLEXES OF QUINACRINE MUSTARD WITH DNA .2. DEPENDENCE ON THE STAINING CONDITIONS

Abstract—Measurements of time‐resolved fluorescence of Micrococcus lysodeikticus DNA stained with quinacrine mustard are presented in this paper. In particular, the dependence of the fluorescence decay law both on the degree of DNA saturation by the dye and on the ionic strength of the solutions is investigated. It is shown that the quinacrine mustard molecules intercalating the DNA base pairs exhibit two different fluorescence behaviors which make them either donors or acceptors in a Forster energy transfer mechanism. A mathematical formulation of this mechanism allows us to interpret all the experimental fluorescence decay curves. In addition, some new properties of the external binding mode are obtained. Copyright © 1979, Wiley Blackwell. All rights reserved