On the interaction of luminol with human serum albumin: Nature and thermodynamics of ligand binding

► Binding of non-polar fraction of luminol into sub-domain IIA of HSA binding sites. ► Additional fast fluorescence decay component of luminol in presence of HSA. ► Bilirubin replaces luminol from protein binding pocket and consequently increases fluorescence yield. ► Binding of luminol in HSA is spontaneous and enthalpy driven process. ► Hydrogen bond formation and/or van der Waals force may be responsible for this binding to occur.