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Fluorescence Decay Heterogeneity Model Based on Electron Transfer Processes in an Enzyme-Ligand Complex

100%

Wlodarczyk J., Kierdaszuk B.

Acta Physica Polonica A

2005

vol. 107

issue 6

883-894

The models are described for complex fluorescence decay of tyrosine in proteins involving continuous distribution of fluorescence lifetimes and electron transfer processes. We introduce the analytical decay function with a power-like term, which provides good fits to highly complex fluorescence decays. Moreover, the power-like term in the proposed decay functions is a manifestation of so-called Tsallis nonextensive statistics and 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, free in aqueous solution and in the complex with formycin A (an inhibitor) and orthophosphate (a co-substrate), and demonstrated that both models reflect the enzyme-ligand interactions. Direct measure of heterogeneity of 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.

Total mercury content in fish from the Gulf of Gdansk

61%

Falandysz J., Piotrowska M., Wlodarczyk J., Chwir A., Marcinowicz^A., Marcinowicz A.

Oceanological Studies

1994

issue 67/10

59-64

Concentratin of total mercury was determined in muscle tissue of cod Gadus morhua, herring Clupea harengus, eel Anguilla anguilla, calpout Zoarces viviparus, perch Perca fluvitalis, pikeperch Stizostedion lucioperca, sand eel Hyperoplus lanceolatus, round goby Negobius melanostomus, brown trout Salmo trutta, trout Salmo gairdneri, flounder Platychtis flesus, turbot Psetta mazima, smelt Osmerus eperlanus and sculpin Cottus scorpius caught in the Gulf of Gdansk in 1986-1993.The measurements of mercury concentrations were performed by the method of cold vapour atomic absorption spectrmetry (CV-AAS), after wet digestion of samples with concentrated nitric acid.The highest mean concentration of mercury was found in eelpout, the lowest one in pikeperch.The possitive linear correlations has been found between the body length and mercury concentration in perch, eelpout, sand launce and flounder.

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1 Acta Physica Polonica A

1 Oceanological Studies

1 2005

1 1994

2 Wlodarczyk J.

1 Chwir A.

1 Falandysz J.

1 Kierdaszuk B.

1 Marcinowicz A.

1 Marcinowicz^A.

1 Piotrowska M.

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Fluorescence Decay Heterogeneity Model Based on Electron Transfer Processes in an Enzyme-Ligand Complex

Total mercury content in fish from the Gulf of Gdansk