ABSTRACT
This chapter examines the cases when ligand binding can be studied by fluorescence. Fortunately, binding can be studied by spectroscopic means, including fluorescence, circular dichroism, analytical ultracentrifugation, and in some cases even UV/VIS absorbance spectrophotometry. A loss of intensity will result from quenching of the fluorophore. A shift in the maximal wavelength of fluorescence will result from a change in the energy gap between the highest occupied molecular orbital of the fluorophore and its first excited state. If our ligand fluoresces, then we must design our experiment measuring at wavelengths that do not include the fluorescence signal of the ligand itself. Fluorescence intensity can be used to monitor ligand binding, whether it increases or decreases. If one has access to a very powerful NMR and is working with a protein that is small enough, then it even becomes possible to study binding and protein dynamics at the same time.
