Block oligopeptides (L‐lysyl)m‐(L‐alanyl)L‐tyrosyl‐(L‐alanyl)n‐ (L‐lysyl)m. I. Synthesis through fragment condensation and characterization

Model peptides containing one aromatic residue were synthesized and characterized in order to investigate their interactions with polynucleotides. Chromatographically pure block oligopeptides ( L ‐alysyl) m ‐( L ‐alanyl) n ‐ L ‐tyrosyl‐ ( L ‐alanyl) n , with n = 3 and m =3 or 6, were prepared by fragments condensation using the mixed anhydride method. The protected fragments were prepared by stepwise addition of amino acid residues through the dicyclohexylcarbodiimide method. The purity of the intermediate coupling product was analyzed by gradient elution chromotography on carboxylmethylcellulose. Both block oligopeptides were isolated by preparative chromatography on carboxymethylcellulose. The different features of these syntheses are discussed.