Membrane Interactions of Novicidin, a Novel Antimicrobial Peptide:

Entry by Angelo Mao, AP 225, Fall 2010

Title: Membrane Interactions of Novicidin, a Novel Antimicrobial Peptide: Phosphatidylglycerol Promotes Bilayer Insertion

Authors: Dorosz J, et al

Journal: J. Phys. Chem. B

Volume: Vol 114(34)

Pages: 11053-11060

Summary

Novicidin is a novel antimicrobial peptide that is an improvement on certain preexisting antimicrobial peptides (such as melittin) in that it more effectively targets bacteria and causes less hemolysis. Through various experiments, the researchers propose that an explanation for this difference is the relative proportion of hydrophobic to hydrophilic elements in novicidin composition, as well as the locations of these elements, which lowers the free energy of novicidin interaction and embedding in negative (bacterial) membranes in comparison to zwitterionic (human) membranes.

soft matter keywords: phosphilipid, membrane, hydrophobic interactions, hydrophilic interactions, free energy

Background

Figure 1. Schematic of novicidin and interaction with negative parts of the membrane.

Figure 2. Helical wheel projection of novicidin.

Novicidin is a peptide derived from a previous antimicrobial candidate, ovispirin, which unfortunately was highly cytotoxic. As shown in figure 1, novicidin is a generally positively charged peptide. The helical wheel projection of novicidin indicates where the positively charged amino acids, lysine and arginine (in gray), are localized. The hydrophobic residues (green and yellow) are situated on the other side of the wheel, leading to a hydrophobic moment (arrow) in the novicidin molecule. From this, one would expect that novicidin would be able to embed itself in phospholipid membranes with its positive charges facing outside and its hydrophobic elements facing the hydrophobic core of the membrane.