A tridecapeptide possesses both antimicrobial and protease-inhibitory activities

A 13-residue synthetic peptide (Rev4) was designed based on indolicidin, an antimicrobial peptide from bovine neutrophils. The synthetic peptide retains high antimicrobial activity. When tested for its stability in tobacco leaf extracts, Rev4 was highly stable compared to another antimicrobial peptide, magainin. When mixed with Rev4, magainin was protected from degradation by the leaf extract. Our results show that Rev4 is a potent protease inhibitor which selectively inhibits three out of four different types of proteases. Four other synthetic peptides were tested and the results were suggestive of no correlation between their antimicrobial and protease inhibitory activities.