Purification and Biochemical Characterization of a Tyrosine Phenol-lyase from Morganella morganii

Tyrosine phenol-lyase (TPL) is a valuable and cost-effective biocatalyst for the biosynthesis of L-tyrosine and its derivatives, which are valuable intermediates in the pharmaceutical industry. A TPL from Morganella morganii ( Mm -TPL) was overexpressed in Escherichia coli and characterized. Mm -TPL was determined as a homotetramer with molecular weight of 52 kDa per subunit. Its optimal temperature and pH for β-elimination of L-tyrosine were 45 °C and pH 8.5, respectively. Mm -TPL manifested strict substrate specificity for the reverse reaction of β-elimination and ortho - and meta -substituted phenols with small steric size were preferred substrates. The enzyme showed excellent catalytic performance for synthesis of L-tyrosine, 3-fluoro-L-tyrosine, and L-DOPA with a yield of 98.1%, 95.1%, and 87.2%, respectively. Furthermore, the fed-batch bioprocess displayed space-time yields of 9.6 g L −1  h −1 for L-tyrosine and 4.2 g L −1  h −1 for 3-fluoro-L-tyrosine with a yield of 67.4 g L −1 and 29.5 g L −1 , respectively. These results demonstrated the great potential of Mm -TPL for industrial application.