Analogs of cyclic AMP (cAMP) are useful from the standpoint of potentially possessing biological properties significantly different from those of cAMP itself, as well as being able to supply valuable information concerning structure-activity relationships and mechanisms of action. Fluorescence techniques are an excellent method for obtaining information of this sort because of the sensitivity to small changes in environment as well as the low concentrations sufficient to obtain meaningful results. Desirable attributes of a fluorescent analog would be high quantum yield, long fluorescence lifetime, and an excitation wavelength at sufficiently low energy to allow excitation without interference from other ultraviolet- absorbing moieties in proteins and nucleic acids. Fluorescence techniques, ranging from simply examining the changes in quantum yield and wavelength of emission with respect to various parameters to the use of fluorescence polarization methods for obtaining information about the actual binding of the coenzyme are then available. © 1974, Elsevier Inc. All rights reserved.