Expression of L-aspartate α-decarboxylase from Corynebacterium glutamicum in Escherichia coli and its application in enzymatic synthesis of β-alanine

Abstract:

[Objective] An L-aspartate α-decarboxylase gene was amplified from Corynebacterium glutamicum and expressed in Escherichia coli, to catalyze L-aspartate to β-alanine. The catalysis characterization of this α-decarboxylase was also studied. [Methods] The Pand gene was amplified from C. glutamicum and cloned into the expression plasmid pET24a(+), the recombinant plasmid was transformed into E. coli BL21(DE3). Pand was then successfully expressed with induction. To explore the enzymatic characteristics of Pand, high purity of Pand was obtained by DEAE ion exchange chromatography and G-75 chromatography. Then the effects of substrate and product on enzymatic conversion were studied. [Results] The Pand constituted more than 50% of the total cell proteins and achieved the activity of 94.16 U/mL analyzed by SDS-PAGE and AccQ·Tag assays respectively. The optimal reaction temperature of the purified Pand was at 55 °C and stable below 37 °C. The optimal reaction pH of Pand was at 6.0 and stable at 4.0?7.0. The enzymatic synthesis was inhibited by L-aspartate and β-alanine. When L-Asp was added in batches with 3 000 U Pand per gram L-Asp, the conversion ratio of 100 g/L L-Asp reached 97.8%. [Conclusion] The L-aspartate α-decarboxylase gene from C. glutamicum was successfully expressed in E. coli.