Engineering Metallo-Enzyme Environments for Selective C-H Activation Chemistry

一个多功能的催化平台的可用性，可以精确地定位和功能化复杂有机分子中的单个C-H键，这将彻底改变我们的合成策略，导致高价值化学品的流线型路线，并支持“绿色”化学工业的发展。虽然小的过渡金属配合物可以实现令人印象深刻的C-H功能化范围，但位点选择性通常由底物的特征决定，而不是由催化剂决定。实现更理想的“催化剂控制”转化的一般方法需要催化剂中的分子识别元件：A)允许精确的底物取向，b)可以调整以改变选择性。原则上，这些要求可以由蛋白质催化剂完美地解决，这些催化剂可以很容易地通过实验室进化适应。然而，酶工程策略目前仅限于自然界的20个氨基酸字母表，这严重限制了我们理解生物催化C-H激活过程的能力，并且进一步限制了金属配位环境的范围，从而限制了蛋白质内部可获得的催化活性。在这项研究中，我们将利用我们实验室现有的先进蛋白质工程技术，将“化学编程”配体和/或贵金属辅助因子安装到选定的酶支架中，为直接探测和调整生物催化C-H功能化机制开辟新的途径。随后，我们将证明所得到的C-H活化催化剂可以使用现代超高通量筛选方法通过扩展遗传密码的定向进化进行系统优化，从而提供具有增强选择性/活性谱的生物催化剂。这种方法结合了小分子催化剂可获得的广泛的C-H功能化，以及蛋白质提供的选择性的精确控制，因此将对整个化学工业的可持续制造产生重大影响。该项目完全符合EPSRC的“催化”和“化学生物学和生物化学”研究领域。

The availability of a versatile catalytic platform to precisely target and functionalize individual C-H bonds in complex organic molecules would revolutionize our synthetic strategies, leading to streamlined routes to high value chemicals and supporting the development of a 'greener' chemical industry. Although an impressive range of C-H functionalizations can be achieved with small transition metal complexes, site selectivity is often determined by features of the substrate, and not by the catalyst. A general approach to achieve the more aspirational 'catalyst controlled' transformations requires molecular recognition elements within the catalyst which: a) allow precise substrate orientation and b) can be tuned to alter selectivity. In principle, these requirements could be perfectly addressed by protein catalysts which can be readily adapted via laboratory evolution. However, enzyme engineering strategies are currently limited to Nature's twenty amino acid alphabet which severely restricts our ability to understand biocatalytic C-H activation processes, and furthermore limits the range of metal co-ordination environments, and thus catalytic activities, that are accessible within proteins.In this studentship we will exploit advanced protein engineering technology available in our laboratory to install 'chemically programmed' ligands and/or noble metal co-factors into selected enzyme scaffolds, opening new avenues to directly probe and tune biocatalytic C-H functionalization mechanisms. We will subsequently demonstrate that the resulting C-H activation catalysts can be systematically optimized via directed evolution with an expanded genetic code using modern ultra-high throughput screening methods, affording biocatalysts with augmented selectivity/activity profiles. This approach merges the broad range of C-H functionalizations accessible with small molecule catalysts with precise control of selectivity provided by proteins, and thus will have major impacts for sustainable manufacturing across the chemical industry.This project is perfectly aligned with the 'Catalysis' and 'Chemical Biology and Biological Chemistry' EPSRC research areas.