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oai:figshare.com:article/32639496 2026-10-01T16:39:34Z portal_1172 item_type_8 month_year_10_2026

The identification, modification and functional assessment of three novel bioactive peptides from the defensive skin secretion of Rana genus frogs Xinze Liu (18418253) PUREID: 587615953 Antimicrobial peptide Rana genus frogs peptide modification The overuse of traditional antibiotics has resulted in bacterial resistance and seriously compromised the therapeutic efficacy of the drugs, making the exploration of new antimicrobials particularly important. Several studies have shown that bio-active peptides have become an important source of new antimicrobial drugs due to their broad-spectrum antibacterial action and lack of susceptibility to resistance, and some of these peptides are already used in clinical therapy. Antimicrobial peptides (AMPs) are available in a wide range of plants and animals, with amphibians being an important source. This study mainly focused on three bioactive peptides derived from different Rana genus frogs, and here were conducted a number of experiments to investigate their antibacterial activity and mechanisms, modified the peptide sequences to increase activity and decrease toxicity, and finally investigate the application of the peptides in various aspects based on their different activities. This research contained three experimental chapters. Based on the experimental results, the first peptide, QUB-1986, and the modified peptide, 2170-2R, were demonstrated to have increased antibacterial action when used in conjunction with antibiotics, as well as an inhibitory effect on various resistant P. aeruginosa strains in the first section. The second peptide, Hejiangin-B1, was modified in the second portion by the addition of hydrophobic amino acids to boost antibacterial action, indicating the effect of hydrophobicity on peptide activity, and by cyclisation to improve peptide stability in salt ion and enzyme environments. The third portion primarily focused on the antimicrobial action of peptides in various acidic environments, with the study's fundamental rationale being to adjust the overall charge number of the peptide utilising the variation in pH.<br><br><i>Thesis is embargoed until 31 July 2029.</i> 2026-10-01T16:39:34Z Text Thesis 10.17034/32639496.v1 https://figshare.com/articles/thesis/The_identification_modification_and_functional_assessment_of_three_novel_bioactive_peptides_from_the_defensive_skin_secretion_of_Rana_genus_frogs/32639496 All Rights Reserved Open Access after 2029-07-31