The bacterial decarboxylase (AMDase) catalyzes the enantioselective decarboxylation of prochiral arylmalonates with high enantioselectivity. Although this reaction would provide a highly sustainable synthesis of active pharmaceutical compounds such as flurbiprofen or naproxen, competing spontaneous decarboxylation has so far prevented the catalytic application of AMDase. Here, we report on reaction engineering and an alternate protection group strategy for the synthesis of these compounds that successfully suppresses the side reaction and provides pure arylmalonic acids for subsequent enzymatic conversion. Protein engineering increased the activity of the synthesis of the (S)‐ and (R)‐enantiomers of flurbiprofen. These results demonstrated the importance of synergistic effects in the optimization of this decarboxylase. The asymmetric synthesis of both enantiomers in high optical purity (>99 %) and yield (>90 %) can be easily integrated into existing industrial syntheses of flurbiprofen, thus providing a sustainable method for the production of this important pharmaceutical ingredient.

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Enzymatic synthesis is a promising approach to produce hyaluronic acid (HA) products with defined molecular weight (MW) and dispersity. We here report on the evaluation of nucleoside triphosphate (NTP) regeneration system for the synthesis of the precursors uridine-5'-diphosphate α-d-N-acetylglucosamine (UDP-GlcNAc) and uridine-5'-diphosphate α-dglucuronic acid (UDP-GlcA) and integration in the one-pot synthesis of HA. By integration of polyphosphate kinase from Ruegeria pomeroyi (RpPPK2-3) into the enzyme cascade to synthesize UDP-GlcA we reached 89 % yield after 1 h with a regeneration cycle number (RCN) of 17. With the UDP-GlcNAc cascade, the ATP concentration was lowered 250-fold and reached 94 % yield after 1 h with an RCN of 234. Integration of the RpPPK2-3 regeneration system in one-pot HA synthesis afforded optimization of MgCl 2 and ATP starting concentrations. With 25 mM MgCl 2 and 0.1 mM ATP, a HA concentration of 0.81 g L À 1 with an average MW of 1.17 MDa and dispersity of about 1.08 and an RCN of 75 was obtained. We conclude that integration of NTP regeneration with RpPPK2-3 expanded the enzymatic possibilities to produce HA with lower range MW.

The enzyme arylmalonate decarboxylase (AMDase) enables the selective synthesis of enantiopure (S)-arylpropinates in a simple single-step decarboxylation of dicarboxylic acid precursors. However, the poor enzyme stability with a half-life time of about 1.2 h under process conditions is a serious limitation of the productivity, which results in a need for high catalyst loads. By immobilization on an amino C2 acrylate carrier the operational stability of the (S)-selective AMDase variant G74C/M159L/C188G/V43I/A125P/V156L was increased to a half-life of about 8.6 days, which represents a 158-fold improvement. Further optimization was achieved by simple immobilization of the cell lysate to eliminate the cost- and time intensive enzyme purification step.

Industrial hyaluronic acid (HA) production comprises either fermentation with Streptococcus strains or extraction from rooster combs. The hard‐to‐control product quality is an obstacle to these processes. Enzymatic syntheses of HA were developed to produce high‐molecular‐weight HA with low dispersity. To facilitate enzyme recovery and biocatalyst re‐use, here the immobilization of cascade enzymes onto magnetic beads was used for the synthesis of uridine‐5’‐diphosphate‐α‐d‐N‐acetyl‐glucosamine (UDP‐GlcNAc), UDP‐glucuronic acid (UDP‐GlcA), and HA. The combination of six enzymes in the UDP‐sugar cascades with integrated adenosine‐5'‐triphosphate‐regeneration reached yields between 60 and 100 % for 5 repetitive batches, proving the productivity. Immobilized HA synthase from Pasteurella multocida produced HA in repetitive batches for three days. Combining all seven immobilized enzymes in a one‐pot synthesis, HA production was demonstrated for three days with a HA concentration of up to 0.37 g L−1, an average MW of 2.7–3.6 MDa, and a dispersity of 1.02–1.03.