Interaction with phospholipids bilayers

Some peptide antibiotics act as trans-membrane ion channels. Vibrational spectroscopy shows that ionophores, such as gramicidin A, valinomycin, nystatin, and amphotericins, interact with phospholipid bilayers (Susi et al., 1979). 

Interaction with phospholipid bilayers of a number of hormones, such as atriopeptin HI, an atrial natriuretic peptide, and of calcitonin was investigated by Surewicz et al. 

The rapid recent growth of research on nanoscale chemistry has afforded another class of multivalent ligand that can interact with phospholipid bilayers. Nanoparticles have... 

Breathing is enabled by lung surfactant, a mixture of proteins and lipids that forms a surface-active layer and reduces surface tension at the air-water interface in lungs. Surfactant protein B (SP-B) is an essential component of lung surfactant. Researchers probed the mechanism underlying the important functional contributions made by the N-terminal 7-residues of SP-B, a region sometimes called the insertion sequence . These studies employed a construct of SP-B, SP-B (1-25,63-78), also called Super Mini-B, which is a 41-residue peptide with internal disulfide bonds comprising the N-terminal 7-residue insertion sequence and the N- and C-terminal helixes of SP-B. CD, solution NMR, and SS NMR were used to study the structure of SP-B (1-25,63-78) and its interactions with phospholipid bilayers. Comparison of results for SP-B (8-25,63-78) and SP-B (1-25,63-78) demonstrates that the presence of the 7-residue insertion sequence induces substantial disorder near the center of the lipid bilayer. ... 

Experiments primarily from the laboratory of Aripov on a CTX isolated from Asian cobra venom also show a direct CTX interaction with phospholipid bilayers. Using spin label probes,the CTX (designated cytotoxin was shown to partially insert into phospholipid bilayers to cause an increase in the order parameter of PA liposomes (58). The CTX also interacts with PC/PS liposomes to cause aggregation, increased membrane permeability and enhanced fusion (59). Insertion of CTX into a PC bilayer containing 10% PA was also shown by x-ray small angle scattering (60). 

Meijer, L. A., Leermakers, F. A. M. and Lyklema, J. (1995). Modeling the interactions between phospholipid bilayer membranes with and without additives, J. Phys. Chem., 99, 17 282-17 293. 

This review describes experimental techniques, then gives some selected results of H, and NMR studies of pressure effects on the structure, dynamics and phase transitions of phospholipid bilayers. Other examples deal with 2D-NOESY experiments on lipid vesicles and pressure effects on the interaction of anaesthetics with phospholipid bilayers. Furthermore, we discuss... 

Tipping, E., Ketterer, B., and Christodoulides, L. (1979). Interactions of small molecules with phospholipid bilayers. Binding to egg phosphatidylcholine of some organic anions (bromosulphophthalein, oestrone sulphate, haem and bilirubin) that bind to ligandin and aminoazo-dye-binding prot [Pg.414]

Benfenati F, Greengard P, Brunner J et al (1989b) Electrostatic and hydrophobic interactions of synapsin I and synapsin I fragments with phospholipid bilayers. J Cell Biol 108 1851-62 Benfenati F, Valtorta F, Chieregatti E et al (1992a) Interaction of free and synaptic vesicle-bound synapsin I with F-actin. Neuron 8 377-86... 

For measurements between crossed mica cylinders coated with phospholipid bilayers in water, see J. Marra andj. Israelachvili, "Direct measurements of forces between phosphatidylcholine and phosphatidylethanolamine bilayers in aqueous electrolyte solutions," Biochemistry, 24, 4608-18 (1985). Interpretation in terms of expressions for layered structures and the connection to direct measurements between bilayers in water is given in V. A. Parsegian, "Reconciliation of van der Waals force measurements between phosphatidylcholine bilayers in water and between bilayer-coated mica surfaces," Langmuir, 9, 3625-8 (1993). The bilayer-bilayer interactions are reported in E. A. Evans and M. Metcalfe, "Free energy potential for aggregation of giant, neutral lipid bilayer vesicles by van der Waals attraction," Biophys. J., 46, 423-6 (1984). 

All prokaryote and eukaryote organisms are bounded by cell membranes that are basically phospholipid bilayers decorated with peripheral (loosely bound) and integral (tightly embedded) proteins. A variety of plant triterpenoid saponins (Table 12.3) and defensive antifungal proteins (Table 12.4) can directly interact with phospholipids and are accordingly likely to act by interfering with cell membrane structure, integrity and permeability. 

Vibrational spectroscopy also shows interactions of polyene antibiotic ion channels nystatin and amphotericin B with phospholipid bilayers (Bunow and Lewin, 1977a Iqbal and Weidekamm, 1979 Van de Ven et al., 1984). In particular, Fourier Transform Raman spectroscopy demonstrates that at high temperature, the amphotericin A complex of DPPC/cholesterol is more ordered, whereas the amphotericin B complex is as ordered as the pure lipid/cholesterol system. In the low temperature phase and in the presence of the sterol-antibiotic complex, the bilayers were suggested to be in the interdigitated state (Levin and Neil Lewis, 1990). 

Cholesterol and membrane proteins, including structural ones such as glycophorin and myelin basic protein and functional ones such as -ATPase, bacteriorhodopsin, and cytochrome c, are important components of biological membranes. Cholesterol-lipid and a number of protein-lipid interactions have therefore been extensively investigated by vibrational spectroscopy. Interactions of hormones and toxins with phospholipid bilayers were also investigated. 

Although DSC and other physical techniques have made considerable contributions to the elucidation of the nature of lipid-protein interactions, several outstanding questions remain. For example, it remains to be dehnitively determined whether some integral, transmembrane proteins completely abolish the cooperative gel-to-liquid-crystalline phase transition of lipids with which they are in direct contact or whether only a partial abolition of this transition occurs, as is suggested by the studies of the interactions of the model transmembrane peptides with phospholipids bilayers (see above). The mechanism by which some integral, transmembrane proteins perturb the phase behavior of very large numbers of phospholipids also remains to be determined. Finally, the molecular basis of the complex and unusual behavior of proteins such as the concanavalin A receptor and the Acholeplasma laidlawii B ATPase is still obscure (see Reference 17). 

A comparison of the different types of motion of the three different variants allows the correlation of the enzyme diffusion behavior with specific stages of the catalytic cycle. TLL, an enzyme which cannot interact strongly with phospholipid bilayers, was found to diffuse quickly on the POPC multilayers with no specific preference for the edge or the top of the layer. The motion detected is most likely associated with weak adsorption and desorption of the enzyme on the layer since the diffusion constant is 100 times slower than that expected for free diffusion in solution [42]. These motions correspond to parts A and eventually B of the catalytic cycle shown schematically in Fig. 25.8. 

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