Biosynthesis of polyamides containing amino acid residues through the specific aminolysis of amino acid ester derivatives

The enzymatic polycondensation of polyamides containing amino acid residues was demonstrated. The diamide monomers, containing amino acid (Phe, Leu, Val) esters at both ends, were synthesized using a Scotten–Baumann reaction. Polymerization was conducted through an enzymatic aminolysis of the ester bond by aliphatic diamine in organic solvents. Several proteases were employed to evaluate the enzyme specificity on the polymerization. α-Chymotrypsin was found to have the most effective catalyst activity on the monomer containing phenylalanine, reflecting the specific enzymatic process. Approximate molecular weight at about 7000 was obtained through this enzymatic polycondensation. The structures of the obtained polymers were confirmed employing IR and NMR spectra. The polymerization occurred in various solvents, including two- and one-phase systems. It is found that water content in organic solvent affects the yield.