Abstract
            Background: LL-37 is one of the well-known antimicrobial peptides which is effective on the extended  expecetrome of microbial pathogens. The aim of this study was to design a modified digital analog of LL-37  with enhanced antimicrobial activity and restricted toxicity of the host cell.  
  Methods: Online databases and software were used for determining LL-37 characteristics such as hydrophobicity,  Booman index, and hemolysis probability. Variant structures based on the replacement of leucine and lysine  with tryptophan and arginine were calculated as well. Finally, the best sequence was selected and analyzed for  approving as an antimicrobial peptide.  
  Results: The antibacterial characteristics of LL-37 were improved by replacing the arginine and tryptophan  and according to systemic calculations, it was defined that this peptide is an antimicrobial peptide by 97%  confidential.  
  Conclusions: In general, bioinformatics tools are considered as one of the most available and efficient tools  for antimicrobial peptide designing. Therefore, future studies could use kLL-39 as an antimicrobial peptide and  investigate its antimicrobial effects in vitro.