Abstract
Amphibian skin is a rich source of biologically active compounds that are assumed to have diverse physiological and defence functions. In addition to the range of pharmacologically active peptides present, skin secretions contain a broad spectrum of antimicrobial peptides (AMPs). So far, these peptides have been studied in only a few species and study of additional species is expected to find further new AMPs. Natural AMPs isolated from the amphibian skin secretions could lead studies of chemical structure analysis and synthesis of novel antimicrobials.In this thesis, the lyophilised skin secretion of Odorrana schmackeri was obtained to examine the structure and bioactivity of the diverse peptides. The biosynthetic precursor cDNA sequence of a peptide, namely Brevinin-1-SHa, was identified through the method of “shotgun” cloning. The mature peptide structure was deduced from this cloned cDNA and isolated from the skin secretion sample by reverse-phase HPLC fractionation. The molecular weight of the peptide was then confirmed by using MALDI-TOF mass spectrometry. Solid phase peptide synthesis (SPPS) was employed to chemically synthesise the peptide. Finally, antimicrobial, anticancer and haemolytic assays were carried out to assess the bioactivity of the peptide.
Structural characterisation of Brevinin-1-SHa showed that it belonged to the known family of Brevinin-1 peptides, which is widely distributed in the genus Rana. The bioactivity assays indicated that Brevinin-1-SHa is a very valuable antimicrobial peptide which has both antibacterial and anticancer activity and is deemed to be non-haemolytic at its effective concentrations.
| Date of Award | 08 Sep 2017 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Christopher Shaw (Supervisor), Tianbao Chen (Supervisor), Mei Zhou (Supervisor), Chengbang Ma (Supervisor), Lei Wang (Supervisor) & Xinping Xi (Supervisor) |