Identification and bioactivity assessment of a protease inhibitor QUB-1833 from the skin secretion of Lithobates catesbeiana

  • Wenqing Liu

Student thesis: Masters ThesisMaster of Philosophy


As bioactive peptides in amphibians gained more and more attention, one of the common frogs, Lithobates catesbeiana, is meaningful to be studied. Its breeding history has lasted for decades, so people already know it quite well. But the research on the bioactive peptides in bullfrogs is not thorough. Therefore, the research objectives in this study are isolation, identification, and bioactivity assessment of bioactive peptides from Lithobates catesbeiana skin secretions.

Using 'shotgun' cloning and DNA sequencing, the peptide sequences were obtained from secretions. Then, the peptide QUB-1833, whose amino acid sequence is SLRGCWTKSYPPQPCL, was selected as the research object. After synthesized by SPPS and purified by RP-HPLC and MALDI-TOF MS, pure peptide powder was got and further its biological activities were evaluated. The peptide QUB-1833 showed a very efficient inhibitory effect on trypsin. While it did not have any inhibitory activity against the selected three microorganisms (S. aureus, E. coli, and C. albicans) and two human cancer cell lines (U251-MG and HCT-116). This peptide has a very low hemolysis activity as well.

In the future, more in-depth research should be based on its good enzyme inhibitory effect, and improves its other bioactivities, so that it can be applied in practice. 
Date of AwardDec 2020
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SupervisorLei Wang (Supervisor) & Mei Zhou (Supervisor)

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