DNA-Ligand Flow Linear Dichroism

Abstract

Synonyms DNA; Induced linear dichroism – ligand–ligand interactions

Definition If we know how the transition moments are oriented within a molecular coordinate framework, we can, from an observed linear dichroism (LD) spectrum, deduce something about how the molecules are aligned within the sample. Since small molecules cannot be flow-oriented, a simple and sometimes very useful application of LD is for detecting interactions between a small molecule and a biological macromolecule such as DNA that can be flow-oriented. Complete absence of a flow LD at the ligand transition wavelengths is generally a safe indication that the dye does not interact with DNA, while the appearance of a ligand LD signal indicates some interaction. The sign and relative amplitude of the measured LD further tells us something about the binding geometry in terms of angles between the absorbing dye transition moments and the DNA helix axis (Rodger and Nordén 1997). Show more