Antibacterial activity of lactophoricin, a synthetic 23-residues peptide derived from the sequence of bovine milk component-3 of proteose peptone

A synthetic peptide of 23 residues corresponding to the carboxyterminal 113 to 135 region of component-3 of proteose peptone (PP3) has been investigated with regard to its antibacterial properties. This cationic amphipathic peptide that we refer to as lactophoricin, displayed a growth-inhibitory activity against both gram-positive and gram-negative bacteria. For most of the strains tested, bacterial growth was observed in the presence of lactophoricin except for Streptococcus thermophilus. In that case, lactophoricin exhibited a minimum inhibitory concentration of 10 muM and a minimum lethal concentration of 20 muM. No hemolysis of human red blood cells was detected for peptide concentrations between 2 to 200 muM, indicating that lactophoricin would be noncytotoxic when used in this concentration range.