Pseudin

Pseudin-2 was shown to have potent antibacterial activity, but a lower cytotoxicity.[8] The cytotoxicity of a peptide can be measured by its effect on human erythrocytes.[9] It takes a lower concentration of Pseudin-2 to kill bacteria or fungi such as E. coli, S. aureus, and C. albicans than to kill human erythrocytes.[8] It is hypothesized that Pseudin-2 binding to the cell membrane of the bacteria results in a conformational change in which the peptide forms an α-helical shape, which allows it to perform cell lysis by inserting itself in the hydrophobic portion of the membrane.[8][9] This mechanism is applicable to similar amphipathic α-helical peptides created by many frog species, although most of these peptides aren't very potent against bacteria.[10] By increasing the cationicity and amphipathic nature of the molecule, it is possible to create analogues of Pseudin-2 that are even more selective towards bacteria. This is done by substituting leucine residues with lysine residues and glycine residues with proline residues, which results in two shorter α-helices (linked by the substituted proline) that are more attuned to penetrating bacterial cell membranes.[9]