The application of fluorescence spectroscopy to the study of drug–protein binding

Many small molecules and drugs bind strongly to the plasma proteins and in particular to human serum albumin or HSA. The degree of binding of a drug to HSA may limit its availability to the receptor sites and excretory systems and so have profound effects on its biological activity and half-life. Various reports of harmful side-effects occurring in vivo and arising from competition between drugs for plasma binding sites have been published. In order to understand and possibly predict these sometimes lethal effects. it is important to develop rapid and reliable methods for studying drug–protein phenomena. Fluorescence spectroscopy is an extremely sensitive technique and fluorescence titrations may be performed quickly and simply. The binding of the fluorescent probes warfarin and 8-anilino-1-naphthalene sulphonic acid has been studied in solutions of HSA and in human sera. An accurate procedure has been developed for the determination of binding constants for such interactions. [Continues.]