A BIOCATALYTIC MICROREACTOR - DYNAMIC CFD MODELLING AND EXPERIMENTAL ANALYSIS Congress: ECAB3 Topic: Biocatalysis and biotransformation

Enantiomerically pure chiral amines are valuable chemical compounds due to their unique ability as intermediate in the pharmaceutical industry. They can be produced by traditional chemical routes, for example by crystallization with chiral carboxylic acids and enantioselective reduction of C = N bonds. However, their chemical synthesis remains a challenge. The possibility of preparing chiral amines using biocatalytic routes is becoming more attractive as a result of recent developments in biocatalyst availability, techniques for improving biocatalyst stability and the high selectivity and catalytic activity of enzyme catalysis (Turner and Truppo, 2010). Among biocatalytic routes, asymmetric synthesis with ω-transaminase (ωTAm) represents one interesting route for the synthesis of optically pure active amines since ω-TAms display high stereoselectivity (Tufvesson et al., 2011). The kinetic mechanism of ω-TAm has been widely studied in laboratory scale batch reactor systems using dilute solutions. A recent trend is the use of miniaturized reaction systems to characterize the performance of biocatalytic reactions. It results in obvious advantages such as the fact that reduced amounts of sample material are necessary, and due to parallelization, the simultaneous performance of experimental studies is facilitated. As a result, more experimental investigations can be performed while less time is necessary for the execution of the experimental investigation. Besides those obvious effects, researchers have moved their interest towards space-confined systems, since they can well mimic the confined and crowded environment in living systems. Often an acceleration of the observed reaction rate can be monitored in microfluidic systems, which is usually caused by an interaction between the unique material transport conditions and reaction rates in such systems. In the here presented work a slow reaction rate is expected and therefore the improved material transport conditions in the microreactor systems are not likely to enhance the overall conversion velocity. This contribution presents the experimental results of ω-transaminase catalyzed reactions. The experiments have been performed in microreactor systems fabricated in silicon/glass and polymers. The performance of the miniaturized systems are compared with batch experiments, performed in 4 mL wells and 100 mL continuously stirred batch reactors. Activity, kinetic parameters and reaction rate in reactors with a different surface-area-to-volume ratio (SA:V) have been measured for the enzyme ω-TAm, in order to determine the dependence of enzymatic reaction kinetics on scale and geometry of the reactor. It has been found that reactor scale and geometry have an influence on the reaction kinetics. To investigate this interesting phenomenon a Computational Fluid Dynamic study has been performed in order to investigate potential explanations for the improvement of the activity in a miniaturized system. Reference 1: Diego Ghislieri and Nicholas J. Turner, Biocatalytic Approaches to the Synthesis of Enantiomerically Pure Chiral Amines, Top Catal (2014), 57:284-300 Reference 2 : Par Tufvesson, Joana Lima-Ramos, Jacob S. Jensen, Naweed Al-Haque, Watson Neto, and John M. Woodley. Process Considerations for the Asymmetric Synthesis of Chiral Amines using !-Transaminase. Biotechnology and bioengineering, 108(7):1479{1493, July 2011. Reference 3 :