Analysis of fluorescence decay kinetics of thioflavin t by a maximum entropy method

The application of a maximum entropy method (MEM) for analysis of time-resolved fluorescence data is discussed. A developed version of MEM has been tested using simulated kinetic data. Based on computed results, practical criteria have been established to determine whether the lifetime distribution of emitting centers is described by a discrete spectrum (a set of two or three exponentials) or by a continuous one (mono- or bimodal distribution of exponentials). The proposed method has been used to analyze the fluorescence decay kinetics of thioflavin T (ThT) intercalated into amyloid fibrils. The presence of two peaks in the lifetime distribution of emitting centers has been explained by the existence in fibrils of two types of binding centers substantially differing in microenvironment rigidity. This suggestion is supported by the results of fluorescence quenching of intercalated ThT with the quencher KI.(authors) Key words time-resolved fluorescence spectroscopy - maximum entropy method - thioflavin T - amyloid fibrils