Biocatalysis for novel drug synthesis: re-purposing haemoproteins for late stage heteroatom and isotope functionalisation of pharmaceuticals

这项工作旨在开发新的酶，使化学家能够以更直接的方式合成复杂的药物化合物。酶是生物催化剂，它们越来越多地被整合到大规模化学生产中（例如用于制药和香精/香料市场）。与传统的化学方法相比，生物催化途径具有许多优势，特别是它们能够在环境无害的条件下对复杂分子进行非常特定的反应。酶的特殊性质使生产过程中的步骤最小化，产生更少的废物，需要更少的能量。然而，酶也有其局限性，特别是当所期望的反应性在其起源的自然生物系统中未知时。这项工作的目标是“设计”酶，使它们能够进行新的非自然反应，否则化学家很难实现。这项工作的目标反应是将碳氢键（C-H）转化为碳氟键（C-F）或碳氘键（C-D）（氘是氢的安全同位素）。虽然这些反应听起来很简单，但它们很难以可控的方式实现，并且通常需要昂贵和浪费的反应程序。然而，C-F和C-D键对于设计新药物化合物的化学家来说是非常有价值的，因为它们可以稳定药物对抗体内的酶（比如肝脏）。肝酶通过攻击C-H键并将其转化为C-OH键来降解药物，并将其从体内清除。因此，在服用药物之前将C-H换成C-F或C-D，可以使药物在体内持续更长时间，从而降低所需的剂量，这对患者非常有益。C-F策略非常有效，2018年批准的药物中约有50%使用了C-F策略。C-D方法较新，但现在也已用于商业药物化合物。不幸的是，目前还没有广泛可用的生物催化途径将C-H转化为C-F和C-D键。创造通往C-F和C-D键的生物催化途径将使新的药物分子更容易制备，使药物化学家能够更快地设计和测试更多的药物，减少浪费。在这项工作中，肝脏（以及自然界其他地方）中发现的酶被用作设计形成C-F和C-D键的新策略的灵感。人工酶仍然需要打破碳-氢键，但随后以不同的方式反应生成碳- f或碳- d，而不是碳- oh。在这个阶段，即使C-F或C-D的新酶只结合到非常小的程度，它也将标志着一个重大的进步，并将使进一步的研究能够使新的行为达到对药物开发和制造有用的水平。因此，这项研究有三方面的好处：(1)它将使从事药物发现的研究人员能够更快、更容易地制造出所需的化合物进行测试。(2)它将使高价值药品的制造商能够建立更可持续的生产实践，(3)它将增加对一类非常重要的酶的功能的理解，这将有利于工业生物技术的其他方面（如风味/香料制造）。因此，这项工作属于BBSRC工业生物技术和生物能源（利用生物资源生产和加工材料、化学品（包括药物前体和生物制药）和能源）的职权范围。从长远来看，它将对英国制药业的经济和公共卫生做出重大贡献。

This work aims to develop new enzymes to allow chemists to synthesise complex drug compounds in a more straightforward manner. Enzymes are biological catalysts, and they are increasingly being integrated into large scale chemical manufacture (such as for the pharmaceutical and flavour/fragrance markets). Biocatalytic routes hold a number of advantages over traditional chemical methods, particularly in their ability to carry out very specific reactions on complex molecules under environmentally benign conditions. The specific nature of enzymes allows the steps in a manufacturing process to be minimised, generating less waste and requiring less energy. However, enzymes have their limitations, particularly if the desired reactivity is not known to occur in the natural biological systems from which they originate. The goal of this work is to "engineer" the enzymes to enable them carry out new non-natural reactions, which are otherwise very difficult for chemists to achieve.The target reaction for this work is the conversion of carbon-hydrogen (C-H) bonds to carbon-fluorine (C-F) or carbon-deuterium (C-D) bonds (deuterium is a safe isotope of hydrogen). Whilst these reactions sound simple, they are very hard to achieve in a controlled manner, and often require costly and wasteful reaction procedures. Yet the C-F and C-D bonds are very valuable to chemists designing new medicinal compounds, because they stabilise the drugs against enzymes in the body, such as the liver). The liver enzymes degrade the drug by attacking the C-H bond and converting it to a C-OH bond, marking it for removal from the body. Hence, swapping the C-H for C-F or C-D before the drug is taken can allow it to last longer in the body and therefore lower the dose required - which can very beneficial for the patient. The C-F strategy is so effective, that it was used in around 50 % of drugs approved in 2018. The C-D approach is newer, but has now been used in commercial drug compounds too. Unfortunately there are currently no widely available biocatalytic routes to converting C-H to C-F and C-D bonds.Creating biocatalytic routes to C-F and C-D bonds would allow new drug molecules to be more easily prepared, allowing medicinal chemists to design and test more drugs more quickly and with less waste. In this work, enzymes like those found in the liver (and elsewhere in nature) are used as inspiration to design new strategies to form C-F and C-D bonds. The artificial enzymes will still be required to break the C-H bond, but then react in a different way to form C-F or C-D rather than C-OH. At this stage, even if the new enzymes for C-F or C-D bonds to only a very small degree, it will mark a major advance, and will enable further study to get the new behaviour to a level where it would be useful for drug development and manufacture. The benefits of this research are therefore three-fold: (1) it will enable researchers working on drug discovery to make desired compounds for testing more quickly and easily. (2) it will enable manufacturers of high-value pharmaceuticals to establish more sustainable manufacturing practices, and (3) it will increase the understanding of the functioning of a very important class of enzymes, which will benefit other aspects of industrial biotechnology (such as flavour/fragrance manufacture). The work therefore falls into the BBSRC remit of Industrial Biotechnology and Bioenergy (the use of biological resources for producing and processing materials, chemicals (including pharmaceutical precursors and biopharmaceuticals) and energy). In the long term, it will make significant contributions to the economy of the UK-based pharmaceutical industry and public health.