Editing Pardaxin (section)

===Antibacterial peptide===
Pardaxin has a helix-hinge-helix structure. This structure is common in peptides that act selectively on bacterial membranes and cytotoxic peptides that lyse mammalian and bacterial cells.<ref name="Oren, Shai 303–310"/> Pardaxin shows a significantly lower [[hemolytic]] activity towards human red blood cells compared to melittin. The C-terminal tail of pardaxin is responsible for this non-selective activity against the [[erythrocytes]] and bacteria.<ref name="Oren, Shai 303–310"/> The amphiphilic C-terminal helix is the ion-channel lining segment of the peptide. The N-terminal α-helix is important for the insertion of the peptide to the [[lipid bilayer]] of the cell.<ref>{{cite journal | vauthors = Shai Y, Bach D, Yanovsky A | title = Channel formation properties of synthetic pardaxin and analogues | journal = The Journal of Biological Chemistry | volume = 265 | issue = 33 | pages = 20202–9 | date = November 1990 | doi = 10.1016/S0021-9258(17)30490-8 | pmid = 1700783 | url = http://www.jbc.org/content/265/33/20202.long | doi-access = free }}</ref>

The mechanism of pardaxin is dependent on the membrane composition. Pardaxin significantly disrupts lipid bilayers composed of [[zwitterionic]] lipids, especially those composed of 1-palmitoyl-2-oleoyl-phosphatidylcholine ([[POPC]]). This suggests a carpet mechanism for cell [[lysis]].<ref name="Hallock 1004–1013">{{cite journal | vauthors = Hallock KJ, Lee DK, Omnaas J, Mosberg HI, Ramamoorthy A | title = Membrane composition determines pardaxin's mechanism of lipid bilayer disruption | journal = Biophysical Journal | volume = 83 | issue = 2 | pages = 1004–13 | date = August 2002 | pmid = 12124282 | pmc = 1302204 | doi = 10.1016/s0006-3495(02)75226-0 | bibcode = 2002BpJ....83.1004H }}</ref> The carpet mechanism is when a high density of peptides accumulates on the target membrane surface. The phospholipid displacement changes in fluidity, and the cellular contents leak out.<ref>{{cite journal | vauthors = Yeaman MR, Yount NY | title = Mechanisms of antimicrobial peptide action and resistance | journal = Pharmacological Reviews | volume = 55 | issue = 1 | pages = 27–55 | date = March 2003 | pmid = 12615953 | doi = 10.1124/pr.55.1.2 | s2cid = 6731487 }}</ref> The presence of anionic lipids or [[cholesterol]] was found to reduce the peptide's ability to disrupt bilayers.<ref name="Hallock 1004–1013"/>