The Interaction of Melittin with E. Coli Membrane: The Role of Cardiolipin

Wei-Chin Hung ； Ming-Tao Lee

《Chinese Journal of Physics》 44卷2期 (2006/04) Pp. 137-149

並列摘要

We studied the interaction of melittin peptide with E. Coli's lipid membrane as a function of the molar peptide-to-lipid ratio (P/L). Two experimental methods were employed. The oriented circular dichroism (OCD) measured the peptide's orientation in the membrane, whereas the lamellar x-ray diffraction (LXD) measured the membrane perturbed by peptides. The result shows that in the measuring range, P/L~1/150 to 1/20, all peptides binding to the membrane adopt a helical conformation, with about 40% of them having a helical orientation normal to the surface (I-state) and the rest parallel to the membrane surface (S-state). In the same P/L range, it appears that the membrane is strongly perturbed by peptides in which the membrane is thinning, and such thinning increases with P/L. Furthermore, we mimiced the E. Coli membrane by two model lipid membranes, one containing cardiolipin while the other does not. We found that cardiolipin is the key lipid component in an E. Coli membrane which enhances the insertion of melittin in the low P/L region.