Optimization and Scale-Up of the DERA Reaction

This reaction is catalyzed by DERA from E. coli. DERA is the only aldolase known which accepts two aldehydes as substrates, offering a versatile approach to 

To overcome problems of poor acceptor substrate acceptance, high concentrations of aldehyde substrates are required to obtain synthetically useful product yields. Unfortunately, DERA shows rather poor resistance to such high aldehyde concentrations, especially toward CIAA, resulting in rapid, irreversible inactivation of the enzyme. Therefore, the organic synthesis of (3R,5S)-6-chloro-2,4,6-trideoxy-hexapyranoside 1 requires very high amounts of DERA. Thus, despite the synthetic usefulness of DERA to produce chiral intermediates for statin side chains, the large-scale application is seriously hampered by its poor stability at industrially relevant aldehyde concentrations. The production capacity for such 2,4,6-trideoxy-hexoses of wild-type E. coli DERA is rather low [15]. 

4 2-DeoxY-D-Rihose 5-Phosphate Aldolase (DERA)-Based Routes to Statin Intermediates 135 OH 

In order to investigate the deactivation of DERA by the reactants that are involved in this reaction, the enzyme was incubated with varying concentrations of acetaldehyde and ClAA, simulating the range of starting concentrahons relevant for industrial applications. Aqueous solutions of the first aldol product (monoaldol) 7 and the final lactol 1 were also prepared according to [24] to investigate the stability of DERA. 

---