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Title: Novel bioactive peptides from the defensive skin secretions of selected frogs
Author: Wu, Yue
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2017
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In the course of this research, skin secretions from three species of frogs, Gunther's frog, Hylarana guentheri, the edible frog, Pelophylax kl. esculentus and the Hejiang odorous frog, Odorrana hejiangensis, were analysed by a range of molecular techniques. Three novel peptides, QUB2495 from the brevinin-1 family, QUB2950 from the brevinin-2 family and a bradykinin-related peptide, QUB1400, were discovered and confirmed in the skin secretion by use of MS/MS fragment sequencing. After this, peptides were synthesised, purified and used in a series of bioactivity assays, such as antimicrobial assays, a haemolysis assay, anticancer cell assays and smooth muscle assays. QUB2495 from Gunther's frog, Hylarana guentheri, display high potency and broad-spectrum of activity against bacterial and cancer cells, however, with high toxicity. QUB2950, from the skin secretion of the edible frog, Pelophylax kl. esculentus, was expected to present broad-spectrum antimicrobial activities and high selectivity, displayed little of these effects. Synthetic analogues, K2991 in which negative amino acids were replaced by Lys showed greatly increased charge, and L3180, in which charge and hydrophobicity are both enhanced by amino acids replacement. Both K2991 and L3180 showed increases in antimicrobial activity and L3180 displayed increased potency against bacterium, cancer cell line and normal cell. QUB1400, which was obtained from the skin secretion of Odorrana hejiangensis, displayed the ability to weakly contract the smooth muscles of rat bladder and uterus.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available