QUB-1157: a bioactive peptide from the skin secretion of the Mexican leaf frog (Pachymedusa dacnicolor)

Abstract

Previous studies demonstrated that amphibians produce an abundance of bioactive peptides in their skin secretions. In this thesis a cDNA precursor encoding a novel peptide was cloned from the skin secretion of Mexican leaf frog, Pachymedusa dacnicolor. The deduced mature peptide was named QUB-1157 due to its molecular mass and consists of nine amino acid residues, pQEYTGWMDF-NH2. A series of biomolecular techniques were used in this thesis. Solid phase peptide synthesis was used to synthesise replicates of the novel peptide, and reversed-phase HPLC and MALDI-TOF MS was applied to purify peptide and confirm the mass. According to the peptide’s sequence, this novel peptide has been classified as a caerulein-like peptide. From the results of all experiments, this novel peptide did not show any significant contractions on the smooth muscle of rat gall bladder, ileum, urinary bladder, uterus and tail artery. Meanwhile, this novel peptide was not found to have any antimicrobial activity against C.albicans, E.coli and S.aureus. QUB-1157 also had no cytotoxicity on horse erythrocytes. However, QUB-1157 inhibited the proliferation of cancer cell line H-157 and U251MG. All these data indicate that it is probably necessary to research more about the structure-function relationship of this novel peptide.

Date of Award	06 Aug 2018
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Mei Zhou (Supervisor), Lei Wang (Supervisor) & Chengbang Ma (Supervisor)