PORE-FORMING PEPTIDE OF ENTAMOEBA-HISTOLYTICA - SIGNIFICANCE OF POSITIVELY CHARGED AMINO-ACID-RESIDUES FOR ITS MODE OF ACTION

Amoebapore is a 77-residue pore-forming peptide from Entamoeba histoly tica with antibacterial and cytolytic properties. It contains eight ly sine residues and one histidine residue. Chemical modifications of amo ebapore with Various reagents affecting either both types of cationic residues or lysine and histidine residues separately resulted in virtu ally complete loss of pore-forming activity. The activity was restored by reversal of modifications. Whereas amoebapore was no longer capabl e of binding to phospholipid vesicles when its lysine residues were mo dified, the modification of the single histidine primarily affected ol igomerization of the peptide upon membrane association.