9 research outputs found
EFFECTS OF THE NDV-GLYCOPROTEINS ON THE ELECTROPERMEABILIZATION OF LIPID BILAYERS
ABSTRACT Newcastle disease virus (NDV) is an enveloped RNA virus. Certain biological activities of the NDV are determined by two surface glycoproteins -haemaglutinin-neuraminidase (HN) and fusion-protein (F). These proteins play an active role in the viru
Importance of interfacial water in permeabilization of ceramide bilayers
The role of structured water at the membrane-
aqueous interface in regulating the water
permeability functions of the epidermal horny layer
(Stratum corneum) is not clear at present. The subject of
this review is the effect of perturbed interfacial water
structure on the relative water permeability properties in
shrinkage experiments of reconstituted vesicle
suspensions of ceramides and cholesterol in the gel
phase. Water structure was perturbed by a series of
reagents known to affect the phase equilibrium of lipid
assemblies. Multilamellar bilayers containing synthetic
ceramides N-palmitoyl-D-L-dihydrosphingosine, and Noleoyl-
D-sphingosine were used as model membranes.
The reagent binding to the ceramide membrane was
determined by fluorescence measurements with 1-
anilino, 8-naphtalene sulphonate (ANS). A dependence
of number of binding sites for ANS on the type of
reagent was found. The change of relative water
permeability with concentration of reagents was studied.
Analysis of these data reveals that the anomalous
behaviour of relative water permeability with the
concentration of reagents used is due to concentrationdependent
structural transitions of the bound water at the
membrane-aqueous interface. Different possibilities of
interaction of the reagents with the interface are
discussed. At the end, it is suggested that the interfacial
water in multilamellar ceramide structures may also
contribute to the water holding and permeability barrier functions of cell membrane complex within the stratum
corneum
GENERAL VIROLOGY EFFECT OF PROTEOLYTIC CLEAVAGE ON THE CONFORMATION OF THE NEWCASTLE DISEASE VIRUS (NDV) MAIN STRUCTURAL GLYCOPROTEIN
ABSTRACT The structural NDV glycoproteins, the haemagglutinin-neuraminidase (HN) and the fusion protein (F
Membrane electropermeabilization effects of frequency and membrane surface order on liposome leakage
Liposomes containing fluorescence marke r
were exposed to an alternating electric field of 80 V
peak to peak square electric waves at diff e r e n t
frequencies 0.01, 1, and 100 kHz to perturb the liposome
permeation. The efflux of fluorescence dye after
application of the electric field was measured by
recording the fluorescence emission due to the complex
formation reaction between the fluorescence dye and
calcium ions in the bulk medium solution. Two
independent sets of experiments were conducted: 1)
calcium ions were present during electropulsation; and
2) they were added after electric field application. Two
parameters, fluorescence emission intensity and
increment of temperature of the solution in the chamber,
were studied. The effect of membrane surface order on
the fluorescence dye leakage from the liposomes wa s
studied by addition of urea at threshold concentration
before the liposomes sealed. The data demonstrate the
existence of frequency dependency window at 1 kHz.
Furthermore, the data were interpreted according to the
theory of interactions of electromagnetic fields with
highly polarized and deformed materials such as
liposome particles. The urea caused an enhancement of
the fluorescence dye leakage at frequency of 100 kHz.
This effect could be explained as a decrease of the
membrane binding rigidity due to the disordering effect
of urea on the membrane lipid surface. Our conclusion is
that the frequency and the membrane surface order are
additional parameters that influence the processes of membrane electropermeabilization