CHEMOENZYMATIC SYNTHESIS OF SPECIFICALLY STABLE-ISOTOPE LABELED L-GLUTAMIC ACID, L-GLUTAMINE AND L-PROLINE

A synthetic scheme has been developed for the preparation of C-13- or N-15-enriched 2-oxoglutaric acid (1), L-glutamic acid (2), L-glutamine (3) and L-proline (4), from simple and commercially available highly enriched synthons. The products have been obtained with high isotope enrichment (> 98%) and high optical purity on a gram scale. The scheme allows the specific labelling of every C- or N-position and any combination of positions. The used combination of organic synthetic steps and enzymatic steps proves to be a very efficient way to obtain optically active biomolecules.