Change of glutamic acid to lysine in a 13-residue antibacterial and hemolytic peptide results in enhanced antibacterial activity without increase in hemolytic activity.

A 13-residue peptide corresponding to a hydrophobic segment of the antimicrobial 47-residue peptide seminalplasmin, PKLLETFLSKWIG (SPF), has been shown to have antibacterial and hemolytic activities (N. Sitaram and R. Nagaraj, J. Biol. Chem. 265:10438-10442, 1990). In an effort to get an insight into the structural and charge requirements for these biological activities, an analog of SPF in which Glu has been replaced with Lys has been synthesized and its antibacterial and hemolytic properties have been examined. It has been demonstrated that the analog, SPFK, exhibits potent antibacterial activity at concentrations at which hemolysis does not occur.