Identification and bioactivity evaluation of a novel peptide from the skin secretion of Pelophylax kl. esculentus

Among these, peptides are found with broad-spectrum antibacterial and antifungal activities, as well as anticancer properties. It is generally assumed that these cationic, amphipathic and α-helical peptides constitute a part of the innate immune system that protects the animal from invasion by pathogenic microorganisms.<br>In this thesis, a novel peptide (QUB-1342) was discovered in the skin secretion of the European edible frog, Pelophylax kl. esculentus.

The precursor structure was found through applying a “shotgun” cloning method, and subsequently translating the cDNA to deduce the mature peptide sequence: FLPIVTGLLSGLL-NH2. From comparison with the sequences of known AMPs, QUB-1342 was classified as a temporin family member. The peptide was chemically-synthesised using solid phase chemistry and afterwards, its molecular mass and purity were confirmed by MALDI-TOF mass spectrometry and reverse phase HPLC. <br>In pharmacological assays, QUB-1342 displayed a weak activity against S. aureus, with an MIC=64μM. It did not show any haemolytic effects at the concentrations employed.