Molecular cloning, peptide synthesis and bioactive assessment of a skin defensive peptide, QUB-2658 from the skin secretion of Limnonectes fujianensis

  • Dongning Li

Student thesis: Masters ThesisMaster of Philosophy


In recent years, research on amphibian skin secretion peptides has become a hot topic for researchers. Antimicrobial peptides (AMPs) from amphibian skin secretion were found to have excellent broad-spectrum antibacterial activities and inhibit drug-resistant bacteria, which made AMPs a potential new antibacterial drug source. Frog skin secretions are the most abundant source of AMPs and thus they have been widely studied by researchers.

In this study, a novel peptide (with an 훼-helix structure) named QUB-2658 (ANMFEDLKNVIKLVEQDRPVLSV-NH2) which does not belong to any known peptide family, has been isolated from the skin secretion of Limnonectes fujianensis. From the same skin secretion, a cDNA library was constructed and subjected to RACE-PCR. The peptide biosynthetic precursor-encoding cDNA sequence was obtained using molecular cloning and Sanger Sequencing. The mature peptide was synthesized by solid phase peptide synthesis, identified and purified by MALDI-TOF mass spectrometry and reverse phase High Performance Liquid Chromatography. Data from antibacterial and anticancer assays showed that the peptide exhibited weak antibacterial activity against S. aureus and E. coli with around 10% inhibition rate at the highest concentration of 512 µM. Additionally, QUB-2658 showed no activity against C. albicans as well as two cancer cell lines, U251-MG and HTC-116, at the highest concentrations. Similarly, it exerted no haemolytic activity with the haemolysis is 5.7% at 512 µM. In future work, modification can try to change specific residues to produce a hydrophobic surface in QUB-2658 with the aim to improve the amphiphilic property of the peptide and maybe its antibacterial activity.
Date of AwardDec 2020
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SupervisorMei Zhou (Supervisor), Lei Wang (Supervisor), Xinping Xi (Supervisor) & Tianbao Chen (Supervisor)

Cite this