Location of chlorhexidine in DMPC model membranes: a neutron diffraction study

Chlorhexidine (CHX) is an effective anti-bacterial agent whose mode of action is thought to be the disruption of the cell membrane. It is known to partition into phospholipid bilayers of aqueous model-membrane preparations. Neutron diffraction data taken at 36 degrees C on the location of CHX in phosphatidylcholine (PC) bilayers is presented. The center of mass of the deuterated hydrocarbon chain of CHX is found to reside 16A from the center of the bilayer in 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (14:0-14:0PC). This places the drug near the glycerol backbone of the lipid, and suggests a mode of action whereby the molecule is bent in half and inserts wedge-like into the lipid matrix. This mechanism is distinct from detergent-like mechanisms of membrane disruption and more similar to some anti-microbial peptide action, where peptides insert obliquely into the bilayer headgroup region to disrupt its structure.