New catalytic reaction development by laboratory evolution of protein-based catalysts

通过开发新的催化反应来生成感兴趣的分子是当前有机化学的一个重要特征。尽管使用小分子和多相催化等经典方法取得了巨大的进展，但许多非常重要的反应没有催化溶液。经典的催化剂类型往往由于催化剂控制的限制而失败。蛋白质是优秀的催化剂，因为它们的大分子结构提供了精确的分子识别。众多活性部位的氨基酸相互作用提供了对底物构象、过渡态和中间体的反应性的独特控制。利用蛋白质活性部位的大量相互作用，我们应该能够克服经典方法无法达到的能量障碍。新的催化反应可以通过蛋白质的大分子结构来实现，这些反应到目前为止还没有在生物学和合成化学中被攻克。建议的艾美诺伊特小组的目标是通过利用蛋白质来开发所需的C-C和C-X键形成反应的催化剂，从而实现高度跨学科的方法。这将通过利用合成有机化学中已知的反应模式、探索各种酶类的催化混杂以及应用最先进的实验室进化实验来实现。在我们的概念论证研究中，我们设想为各种热门反应生成催化剂，包括1)不对称的反Markovnikov烯烃氧化，2)未活化的烯烃的不对称氢化官能化，3)芳烃烷基化反应中的区域控制，或4)以简单烯烃为烯化试剂的羰基烯化反应。后两者将通过建立一个酶催化Lewis酸催化的平台来实现，这将为大量非常重要的C-C键形成反应打开大门。目标反应利用不同的酶类，使用不同的机制，如依赖于金属的氧化化学，依赖于金属的非氧化还原反应以及无辅因子的协作酸/碱催化。这些反应的催化途径具有破坏性的潜力，因为使用化学计量试剂的多步骤反应序列将被可持续的催化转化所取代，这些转化在一次合成操作中选择性地形成所需的键。进化的酶变体将作为机制研究的基础，以了解使这些转化成为可能的分子相互作用，并研究合成的范围和局限性。此外，通过将这些“新的”酶功能与已有的生物催化剂相结合，可以访问全新的合成代谢途径，从而获得更复杂的整体反应。简而言之，提议的艾美诺特小组利用蛋白质工程来实现和理解新的化学转化，并旨在开发一种用于合成化学的新型蛋白质催化剂。

Generating molecules of interest by developing new catalytic reactions is a defining feature in current organic chemistry. Despite tremendous advances using classical approaches, such as small molecule and heterogenous catalysis, many very important reactions do not have a catalytic solution. Classical catalyst types often fail due to limited catalyst control.Proteins are superior catalysts as their macromolecular structure offers precise molecular recognition. The multitude of active site amino acid interactions provide unique control over substrate conformations, transition states and reactivities of intermediates. Capitalizing on this multitude of interactions in protein active sites, we should be able to overcome energy barriers that are unattainable by classical methods. New catalytic reactions can be envisioned that are enabled by proteins macromolecular structure and that have so far not been conquered, neither in biology nor synthetic chemistry.The proposed Emmy Noether group aims for an highly interdisciplinary approach by exploiting proteins to develop catalysts for desired C-C and C-X bond forming reactions. This will be achieved by taking advantage of reactivity patterns known from synthetic organic chemistry, exploring catalytic promiscuity of the myriad of enzyme classes and applying state of the art laboratory evolution experiments. In our proof of concept studies, we envision to generate catalysts for various sought-after reactions including 1) the enantioselective anti-Markovnikov alkene oxidation, 2) asymmetric hydrofunctionalization of unactivated alkenes, 3) regiocontrol in arene alkylation or 4) carbonyl olefination using simple alkenes as olefination reagent. The latter two will be enabled by establishing a platform for enzymatic Lewis acid catalysis that will open the door to a huge variety of very important C-C bond forming reactions. The target reactions harness different enzyme classes and use different mechanisms such as metal-dependent oxidation chemistry, metal-dependent non-redox reactions as well as cofactor-free, cooperative acid/base catalysis. Catalytic access to these reactions has disruptive potential as multi-step reaction sequences using stoichiometric reagents will be replaced with sustainable catalytic transformations that form desired bonds selectively in one synthetic operation. The evolved enzyme variants will serve as basis for mechanistic studies to gain understanding in the molecular interactions that enable these transformations and to study scope and limitations in synthesis. Further, whole new synthetic metabolic pathways will be accessible by combining these “new-to-nature” enzyme function with established biocatalysts to access even more complex overall reactions. In short, the proposed Emmy Noether group exploits protein engineering to enable and understand new chemical transformations and aims to develop a new class of protein-based catalysts for synthetic chemistry.