Characterisation of transaminases for the production of high-value chiral amino alcohol 3- aminobutan-2-ol

Chiral amino alcohols are versatile chemicals that have a range of applications in the pharmaceutical and agrochemical fields, including acting as a building block for drug molecules, influencing drug efficacy, and inhibiting corrosion. The aim of this work was to synthesise 3-aminobutan-2-ol, a chiral amino alcohol, from acetoin using Class III aminotransferases from the thermophilic organisms Thermotoga maritima (Tmar) and Geobacillus stearothermophilus (Gste). Candidate transaminase (TAms) genes were expressed in Escherichia coli (E.coli), purified using affinity chromatography, and the pyridoxal phosphate (PLP) enzyme cofactor was re-incorporated using a refolding approach. The purified enzymes were then shown to be active using HPLC approaches reaching a reaction yield of 0.512% and 0.379% for TAms from Tmar and Gste, respectively. This work paves the way for 3-aminobutan-2-ol production in bacterial species that can be grown in bulk on low value feedstocks for a reduction in costs, whilst possibly offering an efficient and highly selective alternative for chiral amino alcohol synthesis.