Synthesis of oligopeptides as polynucleotide analogs

Several dipeptides which have a nucleic acid base in their side chains were designed as water-soluble nucleotide analogs. Amino acids having a uracil or adenine moiety in the gamma-position were synthesized and were connected with another amino acid (spacer) to afford dipeptides. The oligopeptides were prepared from the dipeptides as monomer units. Although all the oligopeptides having uracil moieties examined were water-soluble as expected, these exhibited no hypochromic effect with poly A or poly dA. Contrary, the oligopeptides with adenines exhibited large hypochromicity (ca. 30%) base-specifically with poly dT or poly U.