Characterisation, bioactivity evaluation and rational modification of bioactive peptides from frog skin secretion

Peptide BR2G was proven to have broad-spectrum antibacterial activity, along with a low haemolytic effect. To further modify and enhance the amphipathicity of the peptide, seven analogues were designed by truncating the Rana Box domain in peptide sequence and replacing negatively charged amino acids with lysine. Experimental results showed that the truncation of the Rana box, could decrease the bioactivity of BR2G.

Moreover, a reasonable increase in the amount of positive charge and amphipathicity of peptide could increase the anti-bacterial effects of BR2G. In summary, BR2G was discovered in frog secretion and peptides, BR2G, BR2G-4K and BR2G-19K, have the potential to become antimicrobial agents.<br><br>In Chapter 5, five truncated derivatives of BR2G were designed based on the prediction of cleavage products after treatment with trypsin and their activities were tested with respect to antibacterial effects, anti-biofilm ability, antibacterial kinetics, anti-proliferation, toxicity and salt stability.

Experimental results showed that truncated peptides lost their bioactivity. In conclusion, BR2G could not maintain activity following trypsin cleavage.<br><br><i>Thesis is embargoed until 31 July 2028.<br><br><br></i>