Protein models representing the structural differences of the four classes of antimicrobial peptides.

<p>Antimicrobial peptides can be grouped into four major classes based on their secondary structures, including the (A) α-helical peptides, (B) peptides composed of a series of β-sheets, (C) peptides that adopt unconventional structures, such as extended helices, and (D) peptides that assemble into loops. All structures were obtained freely from the RCSB Protein Data Bank (PDB) (<a href="http://www.pdb.org/" target="_blank">http://www.pdb.org/</a>) and have been referenced according to their Digital Object Identifier (DOI) <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1001067#ppat.1001067-Berman1" target="_blank">[23]</a>. Additional information for each AMP may be obtained by consulting the RCSB PDB and cross-referencing the DOI.