U. Bakowsky et al., Monomolecular organization of the main tetraether lipid from Thermoplasma acidophilum at the water-air interface, CHEM PHYS L, 105(1), 2000, pp. 31-42
The monomolecular organization of the main tetraether phospholipid from the
archaeon Thermoplasma acidophilum was studied by means of a Langmuir film
balance integrated into a fluorescence microscope. After transfer to solid
surfaces at different pressures the films were further investigated by elli
psometry, small angle X-ray scattering and atomic force microscopy. In orde
r to complete former results about the main tetraether phospholipid of T. a
cidophilum [Strobl, C., Six, L., Heckmann, K., Henkel, B., Ring, K., 1985.
Z. Naturforsch. 40c, 219-222], the thickness and the two-dimensional organi
zation of the monomolecular films were investigated. Two mean heights value
s were determined, one of 1.5-1.8 nm and another one of 4-5 nm, indicative
for two different molecular arrangements. The former one is interpreted as
a 'horseshoe' organization with two polar endings in the aqueous subphase,
whereas the latter appears to represent the upright population of molecules
with one polar end in the subphase and the other one in the air. In freshl
y spread and compressed films small domains of the upright lipid population
are initially observed, which enlarge with increasing pressure. These doma
ins are no longer existent after 12 h of spreading without compression. (C)
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