... We have studied the influence of the N-terminal cluster of hydrophobic aminoacid residues on biological activity of Ltc2a. The deletion of four N-terminal residues one by one resulted in a gradual decrease in haemolytic activity and bactericidal effect against Staphylococcus aureus , whereas activity against Gram-negative bacteria was affected weakly. ... The truncation leads to a decrease in binding affinity at zwitterionic membranes that correlates strongly with a decrease in haemolytic activity. ...