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|Title:||How bradykinin alters the lipid membrane structure: A spin label comparative study with bradykinin fragments and other cations|
|Authors:||Turchiello, R. F.|
Ito, A. S.
Lamy-Freund, M. T.
Universidade de São Paulo (USP)
Universidade Federal de São Paulo (UNIFESP)
dimyristoyl phosphatidylglycerol vesicle
|Citation:||Biopolymers. New York: John Wiley & Sons Inc, v. 54, n. 3, p. 211-221, 2000.|
|Abstract:||Electron spin resonance spectroscopy of several different spin labels was used to comparatively study the interaction of the cationic peptide hormone bradykinin (BK; Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg), and some BK fragments (des-Arg(9)-BK, des-Arg(1)-BK, and Arg-Pro-Pro-Gly-Phe or BK1-5), with anionic vesicles of dimyristoyl phosphatidylglycerol (DMPG). for temperatures above the lipid gel-liquid crystal thermal transition (T-m approximate to 20 degrees C), membrane-incorporated spin labels indicated that all peptides (total concentration of 10 mol % relative to lipid) interact with the bilayer, turning the membrane less fluid both at its surface and center, suggesting a partial penetration of the peptides into the membrane core. However, in the lipid gel phase (t < T-m), BK was found to display a much stronger interaction with the membrane decreasing the bilayer fluidity. At temperatures around 15 degrees C the BK-DMPG system was found to present a hysteresis, evinced by the different electron spin resonance spectra yielded upon cooling and heating the sample. System reversibility was found at all other temperatures (0-45 degrees C). That effect could not be assigned to the BET higher concentration at the membrane surface due to its higher net charge (2(+)) compared to the fragments (1(+)), because ten times more des-Arg(9)-BK (100 mol %) yielded opposite result. Further, that was found to be a result rather different from those elicited by the other cations tested: the monovalent Na+, the divalent Zn2+, and the peptide pentalysine. the data presented here are discussed in the light of the different BK and BK fragments biological activities. (C) 2000 John Wiley & Sons, Inc.|
|Appears in Collections:||Em verificação - Geral|
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