Construction of transaminase library and characterization of the enzymatic properties

Transaminases are one of the most suitable enzymes for making chiral amines which are important precursors for the pharmaceutical and fine-chemical industries. Various transaminases had been identified and used in the synthesis of chiral amines. The construction of transaminase library and the characterization of the enzymatic properties are of great importance to screen the most suitable transaminase for the preparation of certain chemicals.

8 transaminases with both S- and R- selective transaminases from different sources were screened, including Vibrio fluvias, Ochrobactrum anthropic, Chromobacterium violaceum, Escherich coli K12, Aspergillus terreus, Aspergillus fumigatus, Nectria haematococca and ATA117 mutants (used in the manufacture of Sitagliptin). They were expressed in recombinant E.coli, to form a small library of transaminases. The properties of the transaminases in this library were characterized, such as optimum reaction temperature and pH, stability and substrate specificity. It was found that these transaminases differed from each other in those characteristics. For example, R-selective transaminase in the library accepted more amino donors and acceptors then S-selective transaminases. Among them, the transaminase from E.coli was found to be the best catalyst for the preparation of Glufosinate, which is an effective herbicide.