Pardachirus pavoninus

Pardaxin P-2 is a 33 amino acid peptide isolated from the mucc al secretion of the Pacific sole, Pardachirus pavoninus, that exhibits surfactant properties. Pardaxin has been shown to interfere with ion transport in both epithelium and nerve cells. At concentration below 10 mmol T, pardaxin forms voltage-dependent, ion-permeable channels in artificial liposomes. The structure of pardaxin P2 in aqueous trifluoroethanol solution has been determined using the NOE distance restrained/molecular dynamics method. This study showed that the peptide adopts an amphiphilic helix over residues 7-11, a bend at residues 12-13 and another helix over residues 14-26. 

For example, the skin secretion of the fish peacock sole Pardachirus pavoninus (Soleidae), occurring in the Indo-Pacific region, contains linear peptides produced by a series of toxic glands along the bases of dorsal- and anal-fin rays. These toxic peptides, composed of 33 amino (2800 Da), are called pardaxin 1, pardaxin 2 and pardaxin 3. For example, the primary structure of pardaxin 1 is formed by the following sequence of amino acids Gly-Phe-Phe-Ala-Leu-lle-Pro-Lys-lle-lle-Ser-Ser-Pro-Leu-Phe-Lys-Thr-Leu-Leu-Ser-Ala-Val-Gly-Ser-Ala-Leu-Ser-Ser-Ser-Gly-Glu-Gln-Glu. Other pardaxins have similar structures. As with other polypeptides, paradaxins are labile compounds that are relatively easily hydrolysed by proteolytic enzymes, and partly also by cooking. 

Tachibana, K., Sakaitani, M and Nakanishi, K. (1985) Pavoninins, shark-repelling and ichthyotoxic steroid N-acetylglucosamines from the defense secretion of the sole Pardachirus pavoninus (Soleidae). Tetrahedron, 41, 1027—1037. 

THOMPSON SA, TACHiBANA K, NAKANisHi K, KUBOTA I. Melittin-like peptides from the shark-repelling defense secretion of the sole Pardachirus pavoninus. Science 1986 Jul 18 233(4761) 341-3. 

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