Novel biocatalytic reductions for synthesis of chiral amines

Chiral amines are used very widely as chemical intermediates to produce drug molecules. Chiral amines exist in more than one form, called enantiomers, and often only one of them is suitable for use in medicine. However, it is extremely difficult to produce the required enantiomer of many chiral amines by standard chemical techniques. It is much better to use enzymes to produce amines, because many enzymes produce pure enantiomers. However, there are still very few enzymes that are suitable for chiral amine production. In this project, we plan to develop new enzymes to produce chiral amines for drug manufacture. The enzymes are from bacteria that grow without oxygen(anaerobes). These bacteria have very unusual enzymes. The amine-producing enzymes that we have discovered catalyse a wide range of reactions that do not occur in other cells. The project will include purifying and characterising the enzymes. We shall also develop genetically engineered bacteria to use for amine manufacturing, because the anaerobes are not really suitable for use in industry. Ultimately, the new enzymes will make it possible to manufacture existing drugs much more cheaply. Furthermore, it should also become possible to produce new medicines that cannot be made at present.

New enzymes will be developed for preparation of chiral amines. New reductases from anaerobic bacteria will be developed for reduction of C-C double bonds and aliphatic nitro groups. The enzymes will be purified and fully characterised, and the corresponding genes will be cloned in E. coli. The substrate ranges and stereoselectivities of the enzymes will be determined, along with their activities, substrate tolerance and stability. Recombinant production strains will be developed, incorporating gene knockouts to eliminate side reactions if required. In addition, metabolically engineered strains will be developed, incorporating nitroalkene reductase and aliphatic nitroreductase for direct conversion of nitroalkenes to enantiopure aminoalkanes. Initial studies will be done to indicate the best routes for industrial implementation of the new biocatalysts.