Catalytic Synthesis of Pharmaceutical Amides in Water

酰胺键可以说是药物化学中最重要的键，在许多治疗溃疡、高胆固醇和细菌和病毒致病性感染的重要日常药物中发挥着重要作用。因此，寻找原子高效、可持续的绿色合成药物酰胺的化学方法至关重要。然而，用于制备酰胺的工业合成方法受到使用复杂或危险试剂来完成其化学反应并产生大量废物的影响。由于缺乏效率，工业合成化学家越来越多地转向“生物催化”或“工业生物技术”作为合成药物生产分子的首选方法。生物催化剂，如酶或微生物，通常以优异的原子效率和选择性实现化学键的合成，自然也擅长合成酰胺键，这是将蛋白质结构结合在一起的主要键。然而，到目前为止，用于形成酰胺键的生物催化剂在工业应用中很少受到关注，尽管这种酶反应是许多化学家寻找生物催化解决合成问题的首选。这是因为自然界中酰胺键形成的生物催化方法虽然有效，但往往很复杂，很难应用于自然环境之外。最近发现的一组酶，我们称之为酰胺键合成酶（ABSs），为生物催化酰胺键的形成提供了新的和未开发的前景，因为它们的反应化学相对简单，也因为它们形成的酰胺键的种类，比以前的情况更接近于真正的药物兴趣分子。在这个项目中，这是约克大学的生物化学家和合成化学家之间的合作，并与GSK和弗莱堡大学合作，我们建议彻底研究新的ABS酶的合成潜力。首先，我们将使用合成化学和生物催化的混合物来定义天然酶的潜力和局限性。然后，我们将使用最近确定的ABS酶McbA结构来设计酶，扩大其催化合成更广泛的药学相关分子的潜力。我们还将使用现代蛋白质进化技术来适应酶，使其作用于工业合作者感兴趣的替代底物。我们还将在酶辅因子回收中应用新技术，使我们能够扩大酰胺键形成反应，并固定化酶，以建立酰胺合成的流动生物催化系统。最后，我们将abs与其他酶结合，形成“级联”，用于从现成的醇和胺底物合成酰胺。总之，该项目将在生物催化酰胺键形成方面建立一个新的前沿，以期为工业合成药物提供更可持续的化学过程。

The amide bond is arguably the most significant in pharmaceutical chemistry, featuring in a host of important everyday pharmaceuticals for the treatment of ulcers, high cholesterol and pathogenic infections by bacteria and viruses. It is vital therefore that there exist atom efficient and sustainable green chemical methods for the synthesis of pharmaceutical amides. However, industrial synthetic methods for the preparation of amides suffer from the use of complex or hazardous reagents to accomplish their chemistry and generate a large amount of waste. Because of this lack of efficiency, industrial synthetic chemists are increasingly turning towards 'biocatalysis' or 'Industrial Biotechnology' as the preferred method of synthesising molecules for pharmaceutical production. Biocatalysts, such as enzyme or microbes, typically achieve the synthesis of chemical bonds with excellent atom efficiency and selectivity, and Nature is also expert at synthesising amide bonds, which are the major bonds that hold the structure of proteins together. Until now however, biocatalysts for the formation of amide bonds have received little attention for industrial application, even though such enzyme reactions feature at the top of the list for many chemists looking for biocatalytic solutions to synthetic problems. This is because biocatalytic methods for amide bond formation in Nature, while efficient, are often complex, and difficult to apply out of their natural context. A recently discovered group of enzymes, which we have called amide bond synthetases (ABSs), offers new and unexplored promise for biocatalytic amide bond formation, as their reaction chemistry is comparatively simple, and also because the kind of amide bonds that they form, are much more closely related to molecules of real pharmaceutical interest than has previously been the case. In this project, which is a collaboration between biochemists and synthetic chemists at York, and in association with GSK and also the University of Freiburg, we propose to thoroughly investigate the synthetic potential of the new ABS enzymes. First we will define the potential and limitations of the natural enzymes using a mixture of synthetic chemistry and biocatalysis. We will then use the recently-determined structure of the ABS enzyme McbA to engineer the enzyme, expanding its potential for the catalysis of the synthesis of a much wider range of pharmaceutically relevant molecules. We will also use contemporary protein evolution techniques to adapt the enzymes to act on alternative substrates that are of interest to industrial collaborators. We will also apply new techniques in enzyme cofactor recycling to allow us to scale up the amide bond forming reactions, and also immobilise the enzymes in order to establish a flow biocatalysis system for amide synthesis. Finally, we will combine ABSs with other enzymes to create 'cascades' for the synthesis of amides from readily available alcohol and amine substrates. Together, the project will establish a new frontier in biocatalytic amide bond formation with a view to more sustainable chemical processes for the industrial synthesis of pharmaceuticals.