WILKE NATALIA
Congresos y reuniones científicas
Título:
Effect of Zn2+ on interfacial behaviour of diacylglycerol pyrophosphate and their mixtures with phosphatidic acid at the air-water interface
Autor/es:
A.L. VILLASUSO, N. WILKE, B. MAGGIO Y E. MACHADO
Reunión:
Congreso; XXXVIII Reunión anual de la Sociedad Argentina de Biofísica; 2009
Resumen:
Diacylglycerol pyrophosphate (DGPP), a phosphorylated form of phosphatidic acid (PA) found
in plants and yeast but not in mammals, is a minor lipid that accumulates transiently under
various abiotic stresses and during biotic interactions. DGPP formation may attenuate PA
content but DGPP itself might be a signalling lipid. Zinc (Zn2+) is an essential mineral, serving
as a cofactor for a variety of enzymes. Although not demonstrated in vivo, it has been shown
that Zn2+ can associated to DGPP.
In this work we studied the interfacial behavior of DGPP and their mixture with palmitoyl oleoyl
phosphatidic acid (PA) at the air-water interface at pH 8 (both lipids are negativelly harged)
with and without ZnCl2.
It was previously shown that DGPP and POPA form expanded monolayers on NaCl subfases
and that mixed monolayers of both lipids form non ideal mixtures, homogeneous at the
microscopic level (0.06 μm2). The interaction among these lipids leads to a diminution of the
mean molecular area and to an increase of the compressibility at all lateral pressures with a
negative excess free energy of compression.
In the presence of Zn2+, the pure lipids monolayers become more condensed with a molecular
area reduction of about 15% at low lateral pressure; by contrast, the surface behaviour of mixed
monolayers is not affected by Zn2+.
The experiments suggest that Zn2+ interacts with the pure lipid monolayers, confirming that
DGPP interacts with Zn2+ in model systems. Converselly, in the mixed monolayers the lipids are
quite closely packed and Zn2+ appears not capable of affecting the intermolecular packing.
in plants and yeast but not in mammals, is a minor lipid that accumulates transiently under
various abiotic stresses and during biotic interactions. DGPP formation may attenuate PA
content but DGPP itself might be a signalling lipid. Zinc (Zn2+) is an essential mineral, serving
as a cofactor for a variety of enzymes. Although not demonstrated in vivo, it has been shown
that Zn2+ can associated to DGPP.
In this work we studied the interfacial behavior of DGPP and their mixture with palmitoyl oleoyl
phosphatidic acid (PA) at the air-water interface at pH 8 (both lipids are negativelly harged)
with and without ZnCl2.
It was previously shown that DGPP and POPA form expanded monolayers on NaCl subfases
and that mixed monolayers of both lipids form non ideal mixtures, homogeneous at the
microscopic level (0.06 μm2). The interaction among these lipids leads to a diminution of the
mean molecular area and to an increase of the compressibility at all lateral pressures with a
negative excess free energy of compression.
In the presence of Zn2+, the pure lipids monolayers become more condensed with a molecular
area reduction of about 15% at low lateral pressure; by contrast, the surface behaviour of mixed
monolayers is not affected by Zn2+.
The experiments suggest that Zn2+ interacts with the pure lipid monolayers, confirming that
DGPP interacts with Zn2+ in model systems. Converselly, in the mixed monolayers the lipids are
quite closely packed and Zn2+ appears not capable of affecting the intermolecular packing.
