Structure-activity relations of parasin I, a histone H2A-derived antimicrobial peptide.

The structure-activity relations and mechanism of action of parasin I, a 19-amino acid histone H2A-derived antimicrobial peptide, were investigated. Parasin I formed an amphipathic alpha-helical structure (residues 9-17) flanked by two random coil regions (residues 1-8 and 18-19) in helix-promoting environments. Deletion of the lysine residue at the N-terminal [Pa(2-19)] resulted in loss of antimicrobial activity, but did not affect the alpha-helical content of the peptide.