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Proceedings Paper

A new approach to interpretation of heterogeneity of fluorescence decay in complex biological systems
Author(s): Jakub Wlodarczyk; Borys Kierdaszuk
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Paper 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.

Paper Details

Date Published: 7 October 2005
PDF: 8 pages
Proc. SPIE 5862, Diagnostic Optical Spectroscopy in Biomedicine III, 58620X (7 October 2005); doi: 10.1117/12.633038
Show Author Affiliations
Jakub Wlodarczyk, Warsaw Univ. (Poland)
Borys Kierdaszuk, Warsaw Univ. (Poland)

Published in SPIE Proceedings Vol. 5862:
Diagnostic Optical Spectroscopy in Biomedicine III
Mary-Ann Mycek, Editor(s)

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