Alpha helical peptides with broad spectrum antimicrobial activity that are insensitive to salt

The present invention relates to the use of antimicrobial peptides in the inhibition of microbial growth and proliferation. Novel antimicrobial truncated peptides are disclosed which are based upon SMAP 29 and RCAP 18, but which contain a lesser number of amino acid residues yet still retain bactericidal activity. In addition, synthetic peptides based upon the SMAP 29 protein are disclosed which have fewer amino acid residues and include substitutions yet retain substantial activity. The invention also relates to a method of inhibiting microbial growth by administering an effective amount of a peptide in accordance with the invention, or by combining the peptides with other antimicrobial agents or antibiotics.