Alamethicin-lipid interaction studied by energy dispersive X-ray diffraction.
A detailed knowledge of the interaction between bacterial membranes and antibiotics provides important information to prevent high levels of antibiotic resistance exhibited by pathogenic strains. We investigated by energy dispersive X-ray diffraction (EDXD) the structure ordering of dioleoyl-phosphatidylcholine (DOPC) lipid interacting with antimicrobial peptide alamethicin, varying the lipid/peptide (L/P) molar ratio under two different hydration levels. In conditions of full hydration (100%) we found that the bilayer thickness is constant between L/P=20 and L/P=80 indicating that in this range, the system has reached the threshold value for the channel formation, while at the relative hydration of 45% a linear decrease of the bilayer thickness as function of L/P was revealed. The kinetic study of the complex alamethicin-DOPC at different L/P values, shows that the Bragg peak energy variation versus the hydration time has a biexponential behavior characterized by two different time constants.
Domenici
F
F
Dipartimento di Fisica Università di Roma "Sapienza", Italy. f.domenici@caspur.it
Panichelli
D
D
Castellano
A Congiu
AC
D000408:Alamethicin / Q000737:chemistry*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry; D007700:Kinetics; D010713:Phosphatidylcholines / Q000737:chemistry*; D014961:X-Ray Diffraction
D023181:Antimicrobial Cationic Peptides; D010713:Phosphatidylcholines; D000408:Alamethicin; C017251:1,2-oleoylphosphatidylcholine