| Full text | |
| Author(s): |
Ito, Amando Siuiti
[1]
;
Rodrigues, Ana Paula
[1]
;
Pazin, Wallance Moreira
[1]
;
Barioni, Marina Berardi
[1]
Total Authors: 4
|
| Affiliation: | [1] Univ Sao Paulo, Dept Fis, Fac Filosofia Ciencias & Letras Ribeirao Preto, BR-14040901 Ribeirao Preto - Brazil
Total Affiliations: 1
|
| Document type: | Journal article |
| Source: | Journal of Luminescence; v. 158, p. 153-159, FEB 2015. |
| Web of Science Citations: | 10 |
| Abstract | |
We performed an overall analysis of steady state, kinetic and dynamical parameters of phospholipids labeled with 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD), to investigate the structural changes accompanying the phase transition of dimyristoyl phosphatidylglycerol (DMPG) vesicles, under low and high ionic strength conditions. For comparison, we also performed experiments on dimyristoyl phosphatidylcholine (DPPC) vesicles, which exhibit a well-defined thermal phase transition. Fluorescence parameters alone (lifetime, pre-exponential factor, rotational correlation times, and initial anisotropy) do not describe the thermal behavior of the vesicles. Combination of intensity decay and anisotropy decay data allows the calculation of mean anisotropy values, and among the several parameters obtained from time-resolved measurements, the main contribution to the mean anisotropy comes from the residual anisotropy, obtained as the limit value at long times. The results of calculations were comparable to the steady state measurements, and allowed the observation of the dependence between the thermal phase transition in DMPG and the ionic strength of the medium. The presence of NaCl affects the lipid packing leading to structural constraints onto the probes that are systematically higher than those observed in low ionic strength. In low ionic strength the long rotational correlation time of the NBD-PE (NBD-phosphatidylethanolamine) probe presents peculiar behavior, showing transient changes along the broad gel-fluid transition, that occurs parallel to the modifications in the scattering intensity. (C) 2014 Elsevier B.V. All rights reserved. (AU) | |
| FAPESP's process: | 09/54044-3 - Acquisition of a fluorescence correlation spectroscope for the measurement of fluorescence correlation and image capture by fluorescence lifetime |
| Grantee: | Amando Siuiti Ito |
| Support Opportunities: | Multi-user Equipment Program |