Antibacterial peptides in interaction with model membranes studied by various spectroscopic methods
M. Pazderková1,2, , T. Pazderka2, P. Maloň1, E. Kočišová2, K. Hofbauerová2,3, V. Kopecký Jr.2, L. Bednárová1
of Organic Chemistry and Biochemistry AS CR, Flemingovo náměstí 2, Prague 6,
of Physics, Faculty of Mathematics and Physics,
of Microbiology AS CR, Vídeňská 1083,
Naturally occurring antimicrobial peptides (AMPs) represent one successful form of chemical defense of eukaryotic cells against bacteria, protozoa, fungi, and viruses . Many of them have been already isolated, thousands of their synthetic analogs were synthesized and a broad spectrum of their antimicrobial, anticancer and antiviral activities was proven [2, 3]. In spite of large number of known AMPs and their therapeutic potential, exact mechanism of their action remains a matter of controversy.
There is a consensus that these peptides selectively disrupt cell membranes and it is believed that their amphiphatic structure plays an important role in this process. Using various spectroscopic methods it was shown that interaction of AMPs with membranes or with their models lead to changes of their secondary structure. Our aim is to study these peptides in interaction with model phospholipids membranes using circular dichroism, infrared and Raman spectroscopy, and in that way contribute to clarification of these differences.
Here we present spectroscopic studies of peptide Hal-1 (Gly-Met-Trp-Ser-Lys-Ile-Leu-Gly-His-Leu-Ile-Arg-NH2) AMP isolated from the venom of the eusocial bee Halictus sexcinctus, which exhibited potent antimicrobial activity against Gram-positive and Gram-negative bacteria but also noticeable hemolytic activity . Circular dichroism, infrared and Raman spectra of chosen AMP and its analogs in a membrane-mimicking environment showed ability to form a-helical structure whereas the HAL peptide exhibits random coil conformation in water. The attempts to measure HAL peptides in an interaction with liposomes with different kinds of membranes are presented as well.
The Grant Agency of the Czech Republic is gratefully acknowledged for support (No. 208/10/0376).
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