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一种用途广泛、选择性强的生物催化剂。不幸的是，这些生物催化剂的各种应用都受到不良反应平衡的影响，这导致不对称合成的原子效率低。这个问题通常通过努力的策略来弥补，例如，通过与多种生物催化剂的复杂级联反应，过度使用供体胺或具有非酶副反应的特定胺的化学计量学。该方案以集成的工艺概念直接针对反应平衡限制，通过从反应混合物中获得产物胺的原位结晶。产物胺的结晶是通过形成一种几乎不溶的盐来促进的，然后这种盐不断地从反应混合物中除去。这种效应将平衡的位置向产物转移，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尺度的连续过程，包括对未转化底物的完全回收，以提高生物催化反应的整体原子效率。拟议的项目分为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。在选择合适的酸对后，将对盐对进行表征，并优化各种转氨酶的反应条件。随后，将验证包括连续反应概念在内的规模放大。该项目完成了对副产物丙酮酸盐的潜在结晶的研究，这产生了类似的反应平衡位置的转移。

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.