A new approach to interpretation of heterogeneity of fluorescence decay in complex biological systems

Jakub Wlodarczyk; Borys Kierdaszuk

doi:10.1117/12.633038

7 October 2005 A new approach to interpretation of heterogeneity of fluorescence decay in complex biological systems

Jakub Wlodarczyk, Borys Kierdaszuk

Proceedings Volume 5862, Diagnostic Optical Spectroscopy in Biomedicine III; 58620X (2005) https://doi.org/10.1117/12.633038
Event: European Conferences on Biomedical Optics 2005, 2005, Munich, Germany

Abstract

Decays of tyrosine fluorescence in protein-ligand complexes are described by a model of continuous distribution of fluorescence lifetimes. Resulted analytical power-like decay function provides good fits to highly complex fluorescence kinetics. Moreover, this is a manifestation of so-called Tsallis q-exponential function, which is suitable for description of the systems with long-range interactions, memory effect, as well as with fluctuations of the characteristic lifetime of fluorescence. The proposed decay functions were applied to analysis of fluorescence decays of tyrosine in a protein, i.e. the enzyme purine nucleoside phosphorylase from E. coli (the product of the deoD gene), free in aqueous solution and in a complex with formycin A (an inhibitor) and orthophosphate (a co-substrate). The power-like function provides new information about enzyme-ligand complex formation based on the physically justified heterogeneity parameter directly related to the lifetime distribution. A measure of the heterogeneity parameter in the enzyme systems is provided by a variance of fluorescence lifetime distribution. The possible number of deactivation channels and excited state mean lifetime can be easily derived without a priori knowledge of the complexity of studied system. Moreover, proposed model is simpler then traditional multi-exponential one, and better describes heterogeneous nature of studied systems.

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Jakub Wlodarczyk and Borys Kierdaszuk "A new approach to interpretation of heterogeneity of fluorescence decay in complex biological systems", Proc. SPIE 5862, Diagnostic Optical Spectroscopy in Biomedicine III, 58620X (7 October 2005); https://doi.org/10.1117/12.633038

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