The discovery of a bioactive peptide, QUB-1957, from the defensive skin secretion of the Chinese Piebald odorous frog, Odorrana schmackeri

  • Haozhen Zhang

Student thesis: Masters ThesisMaster of Philosophy

Abstract

More and more pathogenic microorganisms have developed drug resistance, which has led to the search for new alternatives to antibiotics as one of the hottest topics nowadays. The frog skin secretion may be a potential source where increasing numbers of antimicrobial peptides (AMPs) have been discovered.

In this study, we discovered a novel peptide QUB-1957 from the skin secretion of the Chinese Piebald odorous frog, Odorrana schmackeri, by the method of “shotgun cloning”. After the Solid-Phase Peptide Synthesis (SPPS) and Reversed-phase high performance liquid chromatography (RP-HPLC) purification, the replicate of pure peptide QUB-1957 was obtained. The primary structure and molecular mass were tested by the Matrix-assisted laser desorption ionisation Time-of-flight mass spectrometry (MALDI-TOF MS). The QUB-1957 appears to belong to the Nigrocin-2 family of AMPs after comparing the sequences through the Basic Local Alignment Search Tool (BLAST) database. The QUB-1957 showed antimicrobial activities against the Gram-positive bacterium, Staphylococcus aureus (MIC=8 µM), and the Gram-negative bacterium, Escherichia coli (MIC=16 µM), and the yeast, Candida albicans (MIC=16 µM). The concentration leading to the 10 % haemolysis was 29.2 µM which was far higher than the minimum inhibitory concentrations (MICs) against the three tested microorganisms.

It is expected that further research on QUB-1957 could help understand the mechanism of AMPs. The discovery of QUB-1957 may work as a template compound for the peptide discovery and further clinical application.
Date of AwardJul 2018
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SupervisorLei Wang (Supervisor), Mei Zhou (Supervisor), Lei Li (Supervisor), Tianbao Chen (Supervisor) & Christopher Shaw (Supervisor)

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