J. Miñones Trillo

Miscibility and Langmuir Studies of the Interaction of E2 (279–298) Peptide Sequence of Hepatitis G Virus/GB Virus-C with Dipalmitoylphosphatidyl Choline and Dimiristoylphosphatidyl Choline Phospholipids

Mixed monolayers of E2(279-298), a synthetic peptide belonging to the structural protein E2 of the GB virus C (GBV-C), formerly know as hepatitis G virus (HGV), and the phospholipids dipalmitoylphosphatidyl choline (DPPC) and dimiristoylphosphatidyl choline (DMPC),which differ in acyl chains length, were obtained at the A/W interface (monolayers of extension) in order to provide new insights on E2/phospholipids interaction. Analysis of the surface pressure-area isotherms, Brewster angle microscopy images, relative thickness, and mean areas per molecule has allowed us to establish the conditions under which the mixed components of the monolayer are miscible or immiscible and know how the level of the E2/phospholipid interaction varies with the composition of the mixed films, the surface pressure, and the hydrocarbon chains length of the phospholipids. The steric hindrance caused by the penetration of the polymer strands into the more or less ordered hydrocarbon chains of the phospholipids was suggested to explain the differences in the peptide interaction with the phospholipids studied. Therefore, the novelty of results obtained with the Langmuir film balance technique, supplemented with BAM images allow us to achieve a deeper understanding of the interaction.

Pressure-area isotherms: the behaviour of cyclosporin/pyrene-labelled phospholipid systems

Systems consisting of cyclosporin A (CsA), a cyclic peptide which is an effective immunosuppressive agent for transplanted organs, and dipalmitoylphosphatidylcholine (DPPC), a liposomal phospholipid, obey the molecular area additivity rule when spread as mixed monolayers at the air/water interface. This behaviour is ascribed to the immiscibility of the system components, which orientate themselves differently on the surface. The insertion of a pyrene residue in the DPPC molecule, whether in the non-polar chain to obtain 1-hexa-decanoyl-2-(1-pyrenedecanoyl)-sn-glycero-3-phosphocholine (H-361) or in the polar group to form N-(1-pyrenesulfonyl)-l,2-phospho-ethanolamine triethylammonium (P-58), has no effect on the surface behaviour of the cyclosporin-phos-pholipid system, which remains additive in its molecular areas and hence immiscible at the interface.

Thermodynamics of the compression of poly(isobutyl cyanoacrylate) monolayers at acid, neutral and basic pH

Poly(isobutyl cyanoacrylate) (PIBCA) monolayers, unlike those of most substances, respond to increased temperature with a decrease in area per monomer unit and a fall in the surface pressures at which surface phase transition and collapse occur. These effects are associated with an increase in entropy during isothermal compression of the film, and are attributed to the rise in temperature causing loss of solvation water, rather than to increased solubility of PIBCA.

Untersuchung monomolekularer Filme von Korksäuren

ZusammenfassungMit der Methode der monomolekularen Oberflächenfilme werden an den Korksäuren: Felonsäure, Felogensäure, Floionsäure und Floionolsäure im Bereich kleiner Oberflächendrucke die Molekulargewichte dieser Säuren bestimmt.

Monolayers of human serum albumin: I. Effect of the solution and method for the spreading

SummaryThe influence of different factors on the spreading of human serum albumin films is studied; factors such as the ionic strength of the spreading solution, nature and concentration of the alcohol used as spreading agent, initial spreading area of the subsolution to which the protein solution was applied and the method for the spreading (direct orTrurnit). The results obtained show that the ideal spreading solution is the buffer ph=5.1,μ=0.01, containing 0.5% amyl alcohol (v:v). TheTrurnits method of spreading proteins showed significant advantage over the direct deposit of drops of the protein solutions.