Lysozyme effect on oleic acid/oleate vesicles.
ABSTRACT We have analysed by means of turbidimetric, dynamic light scattering (DLS), and fluorimetric techniques the effect of lysozyme on negatively charged oleic acid/oleate vesicles. The addition of lysozyme brings about a decrease in optical density of the vesicle population, which finally results in a size distribution of oleate vesicles shifted toward smaller mean diameters. On the contrary, (a) when phosphatidylserine vesicles were used, lysozyme induces an increase of turbidity and a shift toward larger vesicle sizes; and (b) the addition of histone H1 or poly-L-lysine produces an aggregative behavior both in oleate and in phosphatidylserine vesicles. Experiments carried out with calcein-containing vesicles indicate that the observed changes in the lysozyme/oleate system occur with partial leakage of the vesicle content. All this is taken to suggest that the interaction between lysozyme and oleate vesicles is of quite specific nature, and certainly not just due to electrostatic interactions.
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ABSTRACT: The complexes formed by partially folded human and bovine alpha-lactalbumin with oleic acid (OA) have been reported to display selective apoptotic activity against tumor cells. These complexes were named human (HAMLET) or bovine (BAMLET) alpha-lactalbumin made lethal to tumor cells. Here, we analyzed the OA complexes formed by fragments of bovine alpha-lactalbumin obtained by limited proteolysis of the protein. Specifically, the fragments investigated were 53-103 and the two-chain fragment species 1-40/53-123 and 1-40/104-123, these last being the N-terminal fragment 1-40 covalently linked via disulfide bridges to the C-terminal fragment 53-123 or 104-123. The OA complexes were obtained by mixing the fatty acid and the fragments in solution (10-fold and 15-fold molar excess of OA over protein fragment) or by chromatography of the fragments loaded onto an OA-conditioned anion exchange column and salt-induced elution of the OA complexes. Upon binding to OA, all fragments acquire an enhanced content of alpha-helical secondary structure. All OA complexes of the fragment species showed apoptotic activity for Jurkat tumor cells comparable to that displayed by the OA complex of the intact protein. We conclude that the entire sequence of the protein is not required to form an apoptotic OA complex, and we suggest that the apoptotic activity of a protein-OA complex does not imply specific binding of the protein.FEBS Journal 11/2009; 277(1):163-73. · 4.25 Impact Factor
Article: Fatty acid vesicles[show abstract] [hide abstract]
ABSTRACT: Results obtained from recent studies on the preparation and application of fatty acid vesicles are reviewed, focusing on some of the particular properties of fatty acid vesicles in comparison with conventional phospholipid vesicles (liposomes): (i) pH dependency which allows reversible transformations from non-vesicular to vesicular aggregates, and (ii) dynamic features that place fatty acid vesicles in between conventional vesicles formed from double-chain amphiphiles and micelles formed from single-chain surfactants. There are two main research areas in which fatty acid vesicles have been studied actively during the last years: (i) basic physico-chemical properties, and (ii) applications as protocell models. Applications of fatty acid vesicles in the fields of food additives and drug delivery are largely unexplored, which is at least partially due to concerns regarding the colloidal stability of fatty acid vesicles (pH- and divalent cation-sensitivity). Recently, fatty acid vesicles were prepared from highly unsaturated fatty acids (docosahexaenoic acid) and the pH range of vesicle formation could be extended to high or low pH values by preparing mixed vesicles through addition of a second type of single-chain amphiphile that stabilizes the vesicle bilayer but itself is not a fatty acid.Current Opinion in Colloid & Interface Science. 01/2007;