Design and Evolution of Artificial Enzymes with Non-Canonical Organocatalytic Residues

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Traditional methods of producing essential chemicals such as medicines, pesticides and fuels are inefficient, expensive and create a huge burden on the environment. In order to maintain our current standard of living and to make essential products available to the global population, we urgently need to develop clean, efficient and sustainable manufacturing technologies to replace traditional chemical processes. An exciting technology that is already being widely adopted by major chemical companies is called Biocatalysis, whereby microorganisms (e.g. bacteria and yeast) are used to produce large amounts of enzymes (nature's catalysts) which are subsequently used in environmentally friendly processes to efficiently convert starting materials into desired products and high-value intermediates. Importantly, scientists are now able to quickly modify and optimize the natural function and properties of an enzyme to make it suitable for its desired application through a process called directed evolution, which mimics Darwinian evolution on a laboratory timescale. In principal, through directed evolution it should ultimately be possible to replace those chemical processes for which there is a natural counterpart with greener, more efficient biocatalytic alternatives. Unfortunately, to produce our essential chemicals we rely heavily on a series of non-natural reactions, and enzymes capable of performing these transformations simply do not exist. This means that for a typical multi-step sequence required to produce an essential chemical, existing technology may only allow us to replace one or two steps with a clean enzymatic process, with the remaining steps still reliant on hazardous chemical reactions. My research aims to overcome these significant limitations by creating enzymes which are able to efficiently catalyze synthetically valuable, non-natural reactions.Nature's enzymes are made up from various combinations of only twenty standard amino acid building blocks which are generally not suitable to promote non-natural reactions. To achieve the ambitious goal of creating artificial enzymes, we will supply microorganisms with the necessary tools to produce biocatalysts which contain new functional, catalytic amino acids with unique properties. These residues are carefully designed so that they can be produced cheaply, cleanly and efficiently and have the necessary functionality to perform not one, but many important non-natural reactions which are currently carried out using hazardous chemical reagents. The primitive and promiscuous enzymes initially produced are expected to display low activity compared with natural enzymes, since they have not been subjected to millions of years of natural evolutionary processes to optimize their function. However, directed evolution offers an ideal method to rapidly optimize the activity of these biocatalysts to produce specialized, robust enzymes suitable for use in manufacturing processes. These enzymes can be used as standalone catalysts to make high-value intermediates or in multi-step biocatalytic pathways to produce new and existing medicines, pesticides and fuels. Since these essential products will be produced cheaply in an environmentally friendly manner, they will be widely accessible for use by the global population.