Identification and functional study of a nigrocin peptide, QUB-1973, from the defensive skin secretion of the frog, Odorrana andersonii

Here, a nigrocin peptide, QUB-1973, belonging to the brevinin superfamily, was identified in the skin secretions of Chinese Yunnanfu frogs, Odorrana andersonii. The bio-synthetic precursor sequence of QUB-1973 was first obtained via ‘shotgun’ molecular cloning from the skin secretion-derived cDNA library.

The mature peptide (GLLSGVLGVGKKIVCGLSGLC) was then identified by characterising the cleavage site at the N terminus (the common convertase cleavage site, a pair of basic amino acids -Lys-Arg-) of the pro-peptide, along with sequence alignments with other known nigrocin peptides. Thereafter, QUB-1973 was synthesised by solid-phase peptide synthesis (SPPS). The synthetic peptide was then verified and purified by use of MALDI-TOF mass spectrometry and reverse-phase HPLC, respectively.