Synthesis and characterization of polyamides containing unnatural amino acids

We describe the synthesis of several polyamides that retain the secondary structure of proteins and contain derivatizable side chains. The derivatizable side chain allows for further reaction of the polymer chain (e.g., chain cross-linking or addition of pendant groups). Polymers of alpha-amino acids containing a terminal unsaturated bond on the side chain have been synthesized. Poly-L-pentenyl glycine, poly-L-propargyl glycine, and poly-L-allyl glycine were synthesized chemically via Leuchs' anhydrides and enzymatically using subtilisin Carlsberg. Poly-L-propargyl glycine and poly-D,L-allyl glycine folded into the beta-sheet configuration whereas poly-L-pentenyl glycine assumed a helical conformation. The secondary structure of poly-L-allyl glycine and poly-D,L-pentenylglycine could not be determined conclusively. Comparison of properties between the polymers obtained chemically and enzymatically is provided.