Synthesis and Chemical Properties of Poly-α-Amino Acids

The chapter discusses the synthesis and chemical properties of poly-α-amino acids. Poly-α-amino acids are synthetic polymers composed of α-amino acid residues linked by peptide bonds. They are prepared by polymerization of the corresponding monomers and consist, like other synthetic polymers, of mixtures of homologous macromolecules of varying chain length. The preparative methods developed permit the synthesis of a large variety of α-amino acid polymers, in a wide range of average molecular weights. A number of different derivatives of α-amino acids and peptides have been used as monomers for the preparation of poly-α-amino acids; the most suitable and commonly used are the N-carboxy-α-amino acid anhydrides (NCAs). These readily undergo polymerization, with carbon dioxide evolution, to yield the corresponding poly-α-amino acids. The synthesis of amino acid polymers from the monomers may be accompanied by varying amounts of byproducts that should be removed, during the isolation and purification of the polymer. The purification techniques applied are described in the chapter. In addition, the methods used to establish the chemical constitution of the polymers and their average molecular weights are given.