Sphingomyelin-rich domains are sites of lysenin oligomerization: implications for raft studies.

Lysenin is a self-assembling, pore-forming toxin which specifically recognizes sphingomyelin. Mutation of tryptophan 20 abolishes lysenin oligomerization and cytolytic activity. We studied the interaction of lysenin WT and W20A with sphingomyelin in membranes of various lipid compositions which, according to atomic force microscopy studies, generated either homo- or heterogeneous sphingomyelin distribution.

Molecular organization of antifungal antibiotic amphotericin B in lipid monolayers studied by means of Fluorescence Lifetime Imaging Microscopy.

Amphotericin B (AmB) is a life-saving polyene antibiotic used to treat deep-seated mycotic infections. Both the mode of therapeutic action as well as toxic side effects are directly dependent on molecular organization of the drug. Binding of AmB to lipid monolayers formed with dipalmitoylphosphatidylcholine, pure and containing 40 mol% cholesterol or ergosterol, the sterols of human and fungi respectively, has been examined by means of Fluorescence Lifetime Imaging Microscopy.

Anomalously high aggregation level of the polyene antibiotic amphotericin B in acidic medium: implications for the biological action.

Amphotericin B (AmB) is a polyene antibiotic used to treat deep-seated mycoses. Both the therapeutic action and the toxic side effects of this drug are dependent on its molecular organization. AmB appears as a zwitterion at neutral pH owing to NH(3)(+) and COO(-) groups.

Secondary structure and orientation of the pore-forming toxin lysenin in a sphingomyelin-containing membrane.

Lysenin is a sphingomyelin-recognizing toxin which forms stable oligomers upon membrane binding and causes cell lysis. To get insight into the mechanism of the transition of lysenin from a soluble to a membrane-bound form, surface activity of the protein and its binding to lipid membranes were studied using tensiometric measurements, Fourier-transform infrared spectroscopy (FTIR) and FTIR-linear dichroism. The results showed cooperative adsorption of recombinant lysenin-His at the argon-water interface from the water subphase which suggested self-association of lysenin-His in solution.

Effect of antibiotic amphotericin B on structural and dynamic properties of lipid membranes formed with egg yolk phosphatidylcholine.

Amphotericin B (AmB) is a popular antibiotic applied in treatment of deep-seated mycotic infections. The mode of action of AmB is based upon interactions with biomembranes but exact binding properties of the antibiotic to the lipid membranes still remain obscure. Effect of incorporation of AmB into egg yolk phosphatidylcholine membranes in the concentration range from 0.

An effect of antibiotic amphotericin B on ion transport across model lipid membranes and tonoplast membranes.

A pH sensitive fluorescence probe piranine trisulfonate, entrapped inside small unilamellar liposomes formed with egg yolk phosphatidylcholine, was applied to investigate effect of polyene antibiotic amphotericin B (AmB) on proton transport across lipid membranes. Time dependencies of fluorescence-monitored pH changes inside lipid vesicles, upon sudden acidification of the liposome suspension, were analyzed in terms of two-exponential kinetics. It appears that addition of AmB at 3 mol%, with respect to lipid, considerably increases the rate constant of the fast component of proton transport (a change from (60 to 149) x 10(-3)s(-1)) and decreases the rate constant of the slow component (a change from (11 to 5) x 10(-3)s(-1)).

Organization of antibiotic amphotericin B in model lipid membranes. A mini review.

Amphotericin B (AmB) is a polyene antibiotic frequently applied in the treatment of fungal infections. According to the general understanding, the mode of action of AmB is directly related to the molecular organization of the drug in the lipid environment, in particular to the formation of pore-like molecular aggregates. Electronic absorption and fluorescence techniques were applied to investigate formation of molecular aggregates of AmB in the lipid environment of liposomes and monomolecular layers formed at the argon-water interface.

Dimers of polyene antibiotic amphotericin B detected by means of fluorescence spectroscopy: molecular organization in solution and in lipid membranes.

Fluorescence emission from amphotericin B dissolved in 2-propanol-water was recorded in the spectral region 500-650 nm. The fluorescence excitation spectrum corresponds to the absorption spectrum of the monomeric drug. The large energy shift between the excitation and emission bands indicates that emission takes place from an energy level different than that responsible for absorption.