Observing a molecular knife at work.
Sum frequency generation (SFG) vibrational spectroscopy has been employed to study the molecular interactions between a single substrate supported lipid bilayer and an amphiphilic antibiotic compound 1, with a design based on the common structural motif of natural antimicrobial peptides. The interfacial sensitivity of SFG allows real-time in situ monitoring of ordering changes in both leaflets of the bilayer and orientation of 1 simultaneously. A critical concentration of about 0.8 microg/mL of 1 is found, above which the inner leaflet of the bilayer is significantly perturbed. This concentration corresponds well to the minimum inhibition concentration of 1 that is obtained from bacterial experiments. Orientation of 1 in the bilayer is shown to be perpendicular to the bilayer surface, in agreement with simulation results. SFG can be developed into a very informative technique for studying the cell membrane and the interactions of membrane-active molecules.
Department of Chemistry, University of Michigan, Ann Arbor, 48109, USA.
Xiaoyun
X
Chen
Haizhong
H
Tang
Mark A
MA
Even
Jie
J
Wang
Gregory N
GN
Tew
Zhan
Z
Chen
D000577:Amides / Q000737:chemistry*; D000890:Anti-Infective Agents / Q000737:chemistry*; D040761:Biomimetic Materials / Q000737:chemistry; D003198:Computer Simulation; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry*; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
D000577:Amides; D000890:Anti-Infective Agents; D008051:Lipid Bilayers; D010455:Peptides; D010715:Phosphatidylglycerols; C030345:1,2-dipalmitoylphosphatidylglycerol