We have developed two ex-vivo strategies using purified and immobilised enzymes for the production of this key building block. The most efficient, redox neutral system was constructed by combining pyrroline-5-carboxylate reductase with a lysine-6-dehydrogenase and catalytic amount of cofactor.
Following co-immobilisation of both enzymes, a packed-bed reactor was set up in continuous flow which yielded a molar conversion of >99% with 30 min residence time, and a space-time yield up to 2.5 g/L/h.

This work was carried out in the group of Prof. Francesca Paradisi.

Reference:

• D. Roura Padrosa, A. I. Benítez-Mateos, L. Calvey, F. Paradisi;
  "Cell-free biocatalytic synthesis of pipecolic acid: a dual strategy approach and process intensification in flow"
  Green Chemistry, 2020, 22(16), 5310-5316; doi:10.1039/D0GC01817A.
  (Selected as a 2020 HOT Green Chemistry article)