AbstractThe emergence of antibiotic-resistant clinical bacteria strains has promoted numerous researches to focus on novel classes of antimicrobial molecules. Amongst, antimicrobial peptides (AMPs) represent a promising group since they have unique bactericidal mechanisms comparing to their counterparts - antibiotics. Thus, it is hard for multi-resistant bacteria to develop resistance towards AMPs.
In this thesis, a novel peptide named QUB-1984 belonging to the nigrocin-2 family was identified from the skin secretion of Pelophylax nigromaculatus. Primarily, cDNA encoding the biosynthetic precursor was cloned successfully, followed by “molecular cloning” which was used to deduce the mature peptide sequence. Subsequently, a series of technologies (SPPS, HPLC and MALDI-TOF) were used to synthesise, purify and identify the targeted peptide respectively. Afterwards, QUB-1984 was subjected to several functional tests such as antimicrobial, anticancer and haemolytic assays.
The results revealed the mature peptide sequence as follows: GLLGKILGAGKKVL-CGVSGLC. The peptide exhibited potent antimicrobial activity against E. coli, S. aureus and C. albicans, the MIC/MBC were 8/8, 4/8 and 32/128 µM respectively. Meanwhile, it’s haemolytic activity on horse erythrocytes at 512 µM was lower than 20%. Besides, cell viabilities towards H-157 and PC-3 were over 90% under the concentration of 100 µM which showed relatively low cytotoxicity.
It is expected that this study will make contributions to the finding and design of new antimicrobial agents.
|Date of Award||Dec 2019|
|Supervisor||Tianbao Chen (Supervisor), Mei Zhou (Supervisor), Lei Wang (Supervisor) & Chengbang Ma (Supervisor)|