Antimicrobial activity of antimicrobial peptide LPcin-YK 3 derived from bovine 1 lactophoricin 2 3

14 We previously reported on lactophoricin (LPcin), a cationic α-helical antimicrobial peptide 15 derived from bovine milk, which has antimicrobial effects on Candida albicans as well as 16 Gram-positive and Gram-negative bacteria. In this study, we designed the LPcin-YK3 peptide, 17 a shorter analog of LPcin, and investigated its antimicrobial activity. This peptide, consisting 18 of 15 amino acids with + 3 net charges, was an effective antimicrobial agent against the on 19 the Gram-positive strain, Staphylococcus aureus (MIC: 0.62 μg/ml). In addition, the 20 hemolytic activity assay revealed that the peptide was not toxic to mouse and human 21 erythrocytes up to 40 μg/ml. We also used circular dichroism spectroscopy to confirm that 22 peptide in the presence of lipid has α-helical structures and later provide an overview of the 23 relationship between each structure and antimicrobial activity. This peptide is a member of a 24 new class of antimicrobial agents that could potentially overcome the problem of bacterial 25 resistance caused by overuse of conventional antibiotics. Therefore, it could be used as a 26 therapeutic or natural additive, particularly in the cosmetics industry. 27 28