Disulfide engineering on temporin-SHf: Stabilizing the bioactive conformation of an ultra-short antimicrobial peptide.

In Silico searching for short antimicrobial peptides has revealed temporin-SHf as the short (8AA), hydrophobic, broad spectrum, and natural antimicrobial peptide. Important drawback associated with temporin-SHf is the susceptibility of its bioactive conformation for denaturation and proteolytic degradation. In the current report, disulfide engineering strategy has been adopted to improve the stability of bioactive conformation of temporin-SHf. The functionally non-critical Leu4 and Ile7 residues at i and i + 3 position of helical conformation of temporin-SHf were mutated with cysteine disulfide. Designed [L4C, I7C]temporin-SHf was synthesized, characterized using NMR spectroscopy, and accessed for antimicrobial activity. [L4C, I7C]Temporin-SHf adopts helical conformation from Phe3 to Phe8 in the absence of membrane-mimetic environment and retains broad spectrum antimicrobial activity. The reduction potential of cysteine disulfide of [L4C, I7C]temporin-SHf is -289 mV. Trypsin-induced digestion and serum-induced digestion have confirmed the advantage of cysteine disulfide in imparting proteolytic stability to temporin-SHf. Disulfide-stabilized temporin-SHf may serve as a good model for the rational design of temporin-SHf based antibiotics for treatment of infectious diseases.