2026-10-12T05:13:01Z https://api.figshare.com/v2/oai

oai:figshare.com:article/32634669 2026-10-01T16:53:39Z portal_1172 item_type_8 month_year_10_2026

Molecular cloning, structural characterisation and functional study of bioactive peptides from Odorrana versabilis skin secretion Junting Yao (24166527) PUREID: 455569057 Antibiotics amphibian skin secretion antimicrobial peptides (AMPs) protease inhibitor peptide cell penetrating peptide Frogs are well equipped to deal with environmental challenges and are important sources of antimicrobial peptides as a taxon that has lived on Earth for millions of years. This study aimed to identify potent biologically active therapeutic peptides from Odorrana versabilis frogs and to enhance the effectiveness of the therapeutic peptides by structural modification. In Chapter 3, the bioactivity of Brevinin-1Veb was explored, which has been identified as belonging to the brevinin-1 family. The results show that Brevinin-1Veb has moderate antibacterial and anticancer activity accompanied by strong cytotoxicity. Next, analogues K11-BOV and R11-BOV, were found to significantly enhance the parent peptide bioactivity, with the substitution of arginine producing a stronger enhancement than lysine. As the increase in positive charge continued and the positive charge position was adjusted, LR-BOV showed the best biological activity. Furthermore, we confirmed the importance of the Rana box and net charge threshold from the results of NR-BOV, AK-BOV, LRK-BOV and FR-BOV. In Chapter 4, we successfully isolated and identified a novel trypsin inhibitor peptide, Kunitzin-OV2, and its derivative, F9-Kunitzin-OV2, showed inhibition of chymotrypsin. However, the difficulty of Kunitzin-OV2 and its analogue in entering cells or reacting with cell membranes rendered them functionally inactive. It was hypothesised that Kunitzin-OV2 acted on intracellular targets and that its effective activity requires additional 'carrier' assistance to achieve this. Therefore, in Chapter 5, cationic cell-penetrating peptides (CPPs) were used to conjugate to parent peptides. The results showed that the conjugation was effective and non-toxic. All conjugates showed superior antimicrobial activity while also selectively targeting cancer cells without harming normal cells. The analogue with the most outstanding effect was LMWP-F9-Kunitzin-OV2 (LMWP-F9-KOV2), which enhanced the bactericidal capacity of the parent peptide without increasing toxicity, especially against E. coli, and it has also was shown to kill H157 cancer cells in a dose-dependent manner by inducing apoptosis. This cationic CPP conjugation to bioactive peptides is a new idea for peptide drug design, which could provide a practical aid for the bioavailability and targeting of peptides. Thesis is embargoed until 31 July 2028. 2026-10-01T16:53:39Z Text Thesis 10.17034/32634669.v1 https://figshare.com/articles/thesis/Molecular_cloning_structural_characterisation_and_functional_study_of_bioactive_peptides_from_i_Odorrana_versabilis_i_skin_secretion/32634669 All Rights Reserved Open Access after 2028-07-31