Dermaseptins are a family of

peptide Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty am ...

s isolated from skin of the frog genus ''

Phyllomedusa ''Phyllomedusa'' is a genus of tree frogs in the subfamily Phyllomedusinae found in tropical and subtropical South America (south to northern Argentina) and Panama. It has 16 recognised species. Taxonomy The following species are recognised i ...

''. The sequence of the dermaseptins varies greatly but due to the presence of

lysine Lysine (symbol Lys or K) is an α-amino acid that is a precursor to many proteins. Lysine contains an α-amino group (which is in the protonated form when the lysine is dissolved in water at physiological pH), an α-carboxylic acid group ( ...

residues all are cationic and most have the potential to form amphipathic helices in water or when integrated with the

lipid bilayer The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes form a continuous barrier around all cell (biology), cells. The cell membranes of almost all organisms and many viruses a ...

of the bacterial membrane. Clear separation of two lobes of positive and negative intramolecular electrostatic potential is thought to be important in cytotoxic activity. Dermaseptins are typically 27-34

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...

residues in length and were the first vertebrate peptides demonstrated as having a lethal effect on the filamentous fungi implicated in severe opportunistic infections accompanying immunodeficiency syndrome and immunosuppressive drug therapy. Dermaseptin use in a novel drug delivery system has been proposed. The system is based on the affinity of dermaseptins for the plasma membrane of human erythrocytes. After transient loading of the cells with the non-toxic dermaseptin S4 analogue K4–S4(1–13)a, the peptide is transported in the systemic circulation to distant microbial targets. Upon reaching a microorganism for which it has greater affinity the dermaseptin derivative is spontaneously transferred to the microbial membrane where it exerts its membrane-lytic activity.

References

{{Pore-forming toxins Amphibian toxins Peptides

See also

References