Dermaseptin
Encyclopedia
Dermaseptins are one of a number of families of peptide
Peptide
Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...

s that have been identified, isolated and characterised from the Phyllomedusa
Phyllomedusa
Phyllomedusa is a genus of tree frog from Central and South America. It ranges from Costa Rica southward to Argentina. It has around thirty species.-Secretion:...

genus of frogs.

The sequence of the dermaseptins varies greatly but due to the presence of lysine
Lysine
Lysine is an α-amino acid with the chemical formula HO2CCH4NH2. It is an essential amino acid, which means that the human body cannot synthesize it. Its codons are AAA and AAG....

 residues all are cationic and most have the potential to form amphipathic helices in water or when integrated with the lipid bilayer
Lipid bilayer
The lipid bilayer is a thin membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around cells. The cell membrane of almost all living organisms and many viruses are made of a lipid bilayer, as are the membranes surrounding the cell nucleus...

 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 acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

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. In their 2001 article, Feder et al. also discussed a broader application of peptides such as this analogue in the targeting of drug molecules. This “affinity driven molecular transfer” would involve attaching a drug to the peptide which then transports it to the desired site of action.
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