Engineering Enzymes for Pharmaceutical Amide Synthesis

The amide bond is one of 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. In this project we propose to thoroughly investigate the synthetic potential of new enzymes for amide bond formation, and to use these to synthesise amide-containing pharmaceutical compounds. We will define the potential and limitations of new enzymes using a mixture of synthetic chemistry and biocatalysis. We will then solve the structures of the enzymes using X-ray crystallography and use rational enzyme redesign to expand their potential of the enzymes to catalyse the synthesis of a wider range of pharmaceutically relevant molecules.