Methods of peptide preparation

A method of producing a bioactive peptide, wherein said peptide has a length of 12 to 25 amino acids, has at least 3 cationic amino acids and is capable of forming a helix -helix, which method comprises identification of a cationic sector and division of the remaining part of the peptide into three sectors which are substantially the same size, the incorporation opposite the cationic sector of no more than 1 amino acid bulky and lipophilic sector and incorporation into the two sectors flanking the cationic sector of 2 or more bulky and lipophilic amino acids.