Coupled Biochemical Processes for the Synthesis of Unusual Amino Acids

Unnatural and unusual amino acids are being increasingly incorporated into pharmaceuticals as building blocks because of their resistance to normal metabolic degradation. As such, the demand for exotic, enantiopure amino acids is increasing as more of these drugs reach clinical trials and the market. This proposal seeks to develop new opportunities in this area of novel amino acid synthesis, either through improving methodology for the production of existing amino acids by application of biosynthesis or through the development of novel products using a biosynthetic approach. Biosynthetic methodology using enzymes is particularly attractive because it is able to run under sustainable and environmentally friendly conditions, as it does not require excessively high temperature, has biodegradable components and uses water as a solvent. In particular this programme of research will look at newly cloned transaminase enzymes, to identify those which will improve efficiencies and reaction times for the production of amino acids already on the market, as well as novel amino acids for which there is an emerging market. We will examine in detail the reaction characteristics of each enzyme, since there is no literature on those we have isolated, and this will help us predict which will be good candidates for certain transformations. Additionally, we will examine a series of decarboxylase enzymes for their activity and suitability as enzyme partners in the biotransformation process. Selective decarboxylation of the product keto-acid in the transaminase process will allow us to obtain much higher yields and should afford a cleaner process. Chemical decarboxylation agents will also be examined. Other methods will be examined to improve the process such as recycling of the enzymes. The proteins will be purified to see if this also improves the kinetics and allows for less biomaterial to be used. Purified proteins may also afford recycling benefits. Finally, the process will be scaled up, initially to several litres and subsequently to plant-scale with a view to having a process that is suitable for the commercial production of novel L-amino acids.