Abstract
Staphylococcal α-toxin spreads readily as a film on aqueous media; the film contains 3 and 30 times as much protein as in films of mitochondrial structural protein and in a protein monolayer, respetively. The toxin forms a film also by adsorption from the hypophase. The ability of α-toxin both to spread and adsorb at the air-water interface is increased markedly by 6 M urea. Penetration of α-toxin into lipid monolayers is influenced greatly by the chemical structure of the lipid; the ΔΠ values are in the order cholesterol > phosphatidyl choline > phosphatidyl inositol > sphingomyelin > ganglioside. In line with the known binding of gangliosides by histones, penetration of the basic toxin into the air-water interface is inhibited by ganglioside as well as by sulfatide monolayers. Inasmuch as film penetration (ΔΠ) is consistent with anchoring of the protein at the interface, binding of the cationic toxin under the negatively charged monolayers of phosphatidyl inositol, sulfatide, or ganglioside explains the low ΔΠ values observed with these lipids and the known ability of this protein to coat the host membrane. Penetration of α-toxin into lecithin monolayers increases as the protein concentration in the hypophase becomes greater, as the initial pressure of the lipid film becomes smaller, as pH or temperature of hypophase increases.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call