Enhancement of antimicrobial activity of neuropeptide Y by N-terminal truncation

The activity of neuropeptide Y (NPY) against Candida albicans, which was revealed to be fungicidal, was enhanced significantly by the truncation of amino acid residues at the N terminus. The most active peptides (MICs, approximately 1 mu M) were about 10-fold more potent than the intact NPY (MIC, approximately 10 mu M). The enhancement was weakened by the replacement of the N terminus by negatively charged residues and/or acylation of the a-amino group. These results suggest that only the alpha-helical region of NPY is necessary for the antimicrobial activity and that the net charge of the peptide is important for the activity.