The oligomerisation of L-amino acids by papain was studied in a mixer ball mill and in a planetary ball mill. The biocatalyst proved stable under the ball milling conditions providing the corresponding oligopeptides in good to excellent yields and with a variable degree of polymerisation. Both parameters were found to be dependent on the reaction conditions and on the nature of the amino acid (specifically on its side-chain size and hydrophobicity). In addition, the chemoenzymatic oligomerisation was demonstrated by utilising twin-screw extrusion technology, which allowed for a scalable continuous process. Finally, the synthesised oligo(L-Leu) 2b proved to be active as a catalyst in the Juliá–Colonna enantioselective epoxidation of chalcone derivatives.
Ardila-Fierro, K. J., Crawford, D. E., Körner, A., James, S. L., Bolm, C., & Hernández, J. G. (2018). Papain-catalysed mechanochemical synthesis of oligopeptides by milling and twin-screw extrusion: application in the Julia-Colonna enantioselective epoxidation. Green Chemistry, 20(6), 1262-1269 . https://doi.org/10.1039/C7GC03205F