Investigation of complex amino acid- and amine-based in situ-product crystallization strategies in transaminase- and amine dehydrogenase-catalyzed reactions and its development towards flow reaction concepts

转氨酶是合成相关手性胺的非常通用的、选择性的生物催化剂。不幸的是，这些生物催化剂的各种应用遭受差的反应平衡，这导致不对称合成的低原子效率。这一问题通常可以通过有效的策略来弥补，例如，通过使用多种生物催化剂的复杂级联反应，超化学计量使用供体胺或特定胺，并进行非酶促副反应。本项目通过从反应混合物中原位结晶产物胺，直接以集成工艺概念为目标，限制反应平衡。通过形成几乎不溶的盐促进产物胺的结晶，然后将其从反应混合物中连续除去。这种效应使平衡位置向产物移动，同时允许通过过滤简化产物分离程序。这一概念最终将转化为多克规模的连续过程，包括未转化底物的完全再循环，以提高生物催化反应的总体原子效率。该项目分为7个工作包和2个里程碑，涵盖了从早期筛选合适的酸到最终大规模优化反应概念的工作流程。在选择适用的酸后，将表征盐对，并针对各种转氨酶优化反应条件。随后，将验证包括连续反应概念在内的规模扩大。该项目完成了一个潜在的结晶副产品丙酮酸盐，这产生了类似的反应平衡的位置移动的调查。

Transaminases are very versatile, selective biocatalysts for the synthesis of relevant chiral amines. Unfortunately various applications of these biocatalysts suffer from poor reaction equilibria, which result in low atom efficiencies for the asymmetric synthesis. This problem is typically compensated by effortful strategies, e.g. by complex cascade reaction with multiple biocatalysts, an over-stoichiometric use of the donor amine or specific amines with non-enzymatic side reactions.The presented project targets directly the reaction equilibrium limitation with an integrated process concept by an in situ-crystallization of the product amine from the reaction mixture. The crystallization of the product amine is facilitated by the formation of a barely soluble salt, which is then continuously removed from the reaction mixture. This effect shifts the position of equilibrium towards the products and simultaneously allows a simplified product isolation procedure by filtration. This concept will be eventually converted into a continuous process at multi-gram scale including a full recycle of the non-converted substrates to improve the overall atom efficiency of the biocatalytic reaction. The proposed project is structured into 7 work packages and 2 milestones, which span the work flow from the early screening of suitable acids to the final optimized reaction concept at larger scale. After the selection of applicable acids the salt pairs will be characterized and the reaction conditions optimized for various transaminases. Subsequently a scale-up including a continuous reaction concept will be validated. The project is completed with the investigation of a potential crystallization of the co-product pyruvate, which yields an analogous shift of the position of the reaction equilibrium.