Autor(es):
Almeida, Leonor M. 
; Vaz, Winchil L. C. ; Stuempel, Juergen ; Madeira, Vitor M. C.
Data: 1986
Identificador Persistente: http://hdl.handle.net/10316/10296
Origem: Estudo Geral - Universidade de Coimbra
Descrição
Intramolecular excimer formation with the fluorescent probe 1,3-di( 1 -pyrenyl)propane, differential
scanning calorimetry, and X-ray diffraction were used to assess the effect of ethanol, 1-butanol, and 1-hexanol
on the bilayer organization in model membranes, sarcoplasmic reticulum (SR) lipids and native SR
membranes. These alcohols have fluidizing effects on membranes and lower the main transition temperature
of dimyristoylphosphatidylcholine (DMPC), but only 1-hexanol alters the cooperativity of the phase transition
and significantly increases the thickness of DMPC bilayers. The interaction of the three alcohols with the
SR Ca2+ pump was also investigated. Hydrolysis of ATP and coupled Ca2+ uptake are differently sensitive
to the three alcohols. Whereas ethanol and I-butanol inhibited the Ca2+ uptake, I-hexanol stimulated it.
Nevertheless, the energetic efficiency of the pump (Ca2+/ATP) is not significantly affected by ethanol or
1-hexanol, but uncoupling was observed with 1-butanol at high concentrations. The different effects of alcohols
on the activity of SR membranes rule out an unitary mechanism of action on the basis of fluidity changes
induced in the lipid bilayer. Depending on the chain length, the alcohols interact with the SR membranes
in different domains, perturbing differently the Ca2+-pump activity. http://dx.doi.org/10.1021/bi00365a017
