The discovery and functional study of a bioactive peptide, QUB-3000, from the defensive skin secretion of the northern leopard frog, Rana pipiens

AMPs can inhibit and kill gram-negative bacteria, gram-positive bacteria, fungi and even cancer cells. Compared with traditional antibiotics, it is much more difficult for pathogens to develop drug-resistance towards AMPs, which is because of the distinct mechanisms of action of AMPs. <br>In this study, an AMP precursor encoded by a cDNA was isolated and identified from the lyophilised skin secretion of the northern leopard frog, Rana pipiens, by “shotgun” cloning.

According to its molecular mass, the mature peptide was named QUB-3000. Then, QUB-3000 was synthesised by solid phase peptide synthesis (SPPS), purified by RP-HPLC. The purified synthetic QUB-3000 was then subjected to several functional experiments analysis.<br>QUB-3000 exhibited strong antimicrobial ability against the Gram-positive bacterium Staphylococcus aureus and the Gram-negative bacterium Escherichia coli.