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Title: Studies on novel bioactive peptides and their precursors from the skin secretion of the broad-folded frog, Hylarana latouchii
Author: Lin, Yan
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2014
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Since ancient times, substances derived from amphibian skins have been recognised to possess various medicinal properties, In recent years, the peptides from amphibian skin have attracted extensive attention for their profound significance in providing clues directed toward novel drug development, for better understanding of miscellaneous physiological and pathological processes, for elucidation of phylogenetic relationships and for improving taxonomy. Previously, the chemical complexity of the defensive skin secretion of the broad-folded frog, Hylarana latouchii, has not been studied in detail. In this thesis, parallel transcriptomic and peptidomic analyses of the electrically-stimulated skin secretion have enabled the identification and characterisation of seven, biologically-active peptides. Five of these peptides are antimicrobial peptides displaying differential growth-inhibitory activity toward test microorganisms and human cancer cell lines; two of which belong to the previously-identified brevinin-l and temp orin families, while the others show little structural similarity with other antimicrobial peptides and represent the prototypes of a novel peptide family - the hylaranins. Hylaranin-Ll and hylaranin-L2 (two 18-mer structurally-related but distinct peptides) are described in Chapter 3 and hylaranin-L3 (a unique l3-residue peptide) is described in Chapter 5. In Chapter 4, a novel Bowman-Birk-type trypsin inhibitory peptide, pLR-HL, belonging to the pLRlranacyclin family, was identified. By substitution of its Lys8 residue with Phe, the Phe8-pLR-HL analogue was found to be transformed into a chymotrypsin inhibitor. The II -residue canonical reactive loops within each peptide could exert corresponding protease inhibitory activity independently, In Chapter 6, a peptide structurally-related to bombesin was isolated and found to possess contractile activity on rat urinary bladder and uterus smooth muscles. These data illustrate that amphibian skin continues to provide numerous novel peptides for furthering research in the fields of pharmaceutical science, biological chemistry, medical science, and systematics. It is expected that many more novel amphibian skin peptides are awaiting discovery.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available