Linear Scorpion Peptides: An unexplored pool for peptide hydrogels

Scorpions during their long evolutionary existence on the planet, more than 400 million years, managed to develop series of venom peptides that display diverse biological activities and pharmacological functions. Scorpion venom peptides are generally classified into two main groups: the disulfide bridged peptides (DBPs) which usually target membrane bound ion channels and then non-disulfide bridged peptides (NDBPs), a smaller group with multifunctional activities.

Our current study focuses on the short (13-19 amino acids) antimicrobial linear scorpion peptides. Many of these peptides contain sections, ranging from short to long, of identical amino acid sequences. Most of them display a net positive charge of 1 or 2, exhibit isoelectric point at pH 9-10, have a broad range of hydrophobicity and grand average of hydropathy (GRAVY). These features allow these peptides to be attracted toward the negatively charged phospholipid head groups of the lipid membranes of target cells, a force driven by electrostatic interactions.

Here we present the synthesis of Mucroporin peptide, a 17 amino acid linear peptide isolated from the venom of Lychas Mucronatus, and its synthetic analogs. Mucroporin exhibits positive charge 1 due to a Lysine at the C-terminus site of the peptide. The rest of the peptides are mainly aliphatic, leucine, glycine or isoleucine. A series of synthetic analogs are designed, synthesized, purified, and characterized with liquid chromatography - mass spectrometry techniques (LC-PDA-MS) and nuclear magnetic resonance spectroscopy (NMR). Mucroporin as well as its synthetic analogs are tested with various techniques for their ability to form hydrogels under several conditions.