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oai:figshare.com:article/32629953 2026-10-01T17:29:44Z portal_1172 item_type_8 month_year_10_2026

Identification and functional evaluation of a bioactive peptide QUB-1369 Secreted from the skin of The Common Frog (Rana Temporaria) Haiyi Liu (782240) PUREID: 219992433 Antimicrobial peptides (AMPs) are host defence peptides found abundantly in amphibian skin secretions. They have broad antimicrobial spectrum of Gram-positive bacteria, Gram-negative bacteria, fungi and viruses. In this study, skin secretion of the common frog, Rana temporaria, was used to build a cDNA library by mRNA transcription. A cDNA encoding a peptide biosynthetic precursor transcript was consistently cloned from this by “shot-gun” cloning. The precursor peptide sequence was analysed by bioinformatics tools such as NCBI-BLAST, while Uniprot identified the mature peptide sequence (FLPIVGKLLSGLL-NH2). Then, using Fmoc solid -phase peptide synthesis, the peptide chain was assembled stepwise and attached to resin support. After the peptide was assembled, it was removed from the resin to obtain a crude linear peptide. Reverse-phase HPLC was used to obtain a purified peptide and in accordance with its molecular mass obtained by MALDI-TOF MS, the peptide was named QUB-1369. Antimicrobial assays showed that QUB-1369 was active against Gram-positive bacterium, Staphylococcus aureus and the yeast, Candida albicans at concentrations of 8 µM and 128 µM, respectively. It was not active against Gram-negative bacterium, Escherichia coli. Haemolysis assay of QUB-1369 using horse erythrocytes, showed it was active at a concentration of 16 µM. Anticancer assay found a weak inhibition of HCT 116 Human Colon Carcinoma cells at a concentration of 100 µM. 2026-10-01T17:29:44Z Text Thesis 10.17034/32629953.v1 https://figshare.com/articles/thesis/Identification_and_functional_evaluation_of_a_bioactive_peptide_QUB-1369_Secreted_from_the_skin_of_The_Common_Frog_Rana_Temporaria_/32629953 All Rights Reserved