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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:03 |
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Conference: Bucharest University Faculty of Physics 2004 Meeting
Section: Electricity and Biophysics
Title:
Effect of ionizing radiation on the structure of gramicidin A
molecules inserted into lipid bilayers
Authors:
Maria Nae1, Doina M.Gazdaru1, M. Radu2
Affiliation:
University of Bucharest, Faculty of Physics
Horia Hulubei National Institute for Physics and Nuclear Engineering
E-mail
doinagazdaru@fpce1.fizica.unibuc.ro
Keywords:
artificial membranes, model, gamma radiation
Abstract:
We are reporting preliminary results related to the effects of gamma ionizing radiation on the structure of an artificial membrane model. Methods: We have developed a special experimental protocol in order to obtain reproducible results on phosphatidilcholine liposomes doped with gramicidin A. Turbidimetric measurements were used for the qualitative characterization of the liposomes. The presence of gramicidin A molecules in the lipid bilayer of liposomes was put in evidence by means of steady-state fluorescence spectrometry. The liposome suspensions were irradiated with gamma radiations produced by a cobalt source and the effect was followed by recording the fluorescence spectrum of gramicidin A tryptophan residues. Results: The effect of gamma radiation (0 - 400 Gy) was measured by the relative variation of the fluorescence intensity of gramicidin A tryptophan residues. The maximum value of emitted light decreases with the increasing doses (relative changes are up to 0.50), proving thus the effect of irradiation on the structure of gramicidin A channel. A second observed aspect was the contrary effect of dose rate on the fluorescence intensity. In this case, the relative change of the maximum emitted light decreases linearly with the increasing dose rate, for the same dose of irradiation (100 Gy, in our case). Conclusion: The results prove the indirect effect of gamma radiation on the structure of tryptophan residues from gramicidin A. Our observations on gramicidin A, inserted into lipid bilayers, confirm the results published in the literature on the influence of ionizing radiations on the gramicidin A channels.
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