Evaluating bioactivity of a novel peptide QUB-2456 from the skin secretion of the frog Hylarana Guentheri

A cDNA library was constructed by using the isolated mRNA from the skin secretion with the 'shotgun' cloning procedure. The mature peptide was deduced from the cloned precursor, and the sequence was determined as FLGAVLKVAGKLVPAAICKISKKC, which is belonged to Brevinin-1 family.

Solid phase peptide synthesis (SPPS) was employed to chemically-synthesis the peptide, and the novel peptide was purified and confirmed by reverse phase HPLC and MALDI-TOF mass spectrometry.<br><br>The novel peptide, named QUB-2456, exhibited potent and broad-spectrum antimicrobial activity. MIC values were 2 μM against S.aureus; 4 μM against E.coli; 2 μM against C.albicans. In addition, the haemolysis activity of QUB-2456 dramatically increased when the concentration was above 16 μM. A second peptide, QUB-1667 (FLGAVLKVAGKLVPAAI) was derived from QUB-2456 by excluding the Rana-box, and synthesized to determine its biological activities. <br><br>The results implicated that QUB-1667 did not show any inhibition of microbial, which proved the existence of Rana-box is significant for the antimicrobial activity for QUB-2456.