Chemoenzymatic Synthesis of Poly(l-alanine) in Aqueous Environment

• Published in: Biomacromolecules 2012-04, Vol.13 (4), p.947-951
• Main Authors: Baker, Peter James, Numata, Keiji
• Format: Article
• Language: English
• Subjects: Hydrogen-Ion Concentration; Hydrophobic and Hydrophilic Interactions; Molecular Structure; Papain - chemistry; Papain - metabolism; Peptides - chemical synthesis; Peptides - metabolism; Water - chemistry; Water - metabolism
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm201862z

l-Alanine ethyl ester was polymerized into poly­(l-alanine) (polyAla), one of the insoluble polypeptides, by papain in aqueous buffer at varying pH. At neutral pH, a maximum chain length of 11 repeats was observed. These polymers were dominated by random coiled structure and demonstrated a lack of patterned macromolecular assembly. Under alkaline conditions, longer polymer chain lengths were achieved, and the maximum chain length was 16 repeats. These longer chains showed distinct β-sheet formation and were capable of fibril assembly. The present study reports on chemoenzymatic synthesis of a hydrophobic homopolypeptide under aqueous conditions as well as demonstrates a chain length dependency of secondary structure formation and macromolecular assembly of chemoenzymatically synthesized polyAla, providing a new insight into material design of polypeptide.