Characterization and application of a recombinant dopa decarboxylase from Harmonia axyridis for the efficient biosynthesis of dopamine

Here, a dopa decarboxylase (DDC) from Harmonia axyridis was heterogeneously expressed in Escherichia coli for the efficient biosynthesis of dopamine. For the production of recombinant DDC, the cultivation conditions including IPTG concentration, temperature and induction time were optimized and obtained an optimal specific enzyme activity of 51.72 U.mg(-1) crude extracts. After the purification of DDC with a recovery yield of 68.79%, its activity was further characterized. The V-max, K-m, K-cat, and K-cat/K-m of DDC for dihydroxyphenylalanine (dopa) were 0.02 mmol.ml(-1) .s(-1), 2.328 mmol.ml(-1), 10435.90 s(-1) and 4482.77 ml.mmol(-1) .s(-1), respectively. The highest DDC activity was observed at the condition of pH 7.5 and 45 C. With the purified DDC, the feasibility to produce dopamine from L-dopa was evaluated. The optimal yield was determined at the following bioconversion conditions: pH of 7.0, the reaction temperature of 40 degrees C, 0.4 mmol.L-1 of PLP and 4 g.L-1 of L-dopa. Subsequently, a fed-batch process for the production of dopamine was developed and the effect of oxygen was evaluated. The titer, yield and productivity of dopamine reached up to 21.99 g.L-1, 80.88% and 14.66 g.L-1 .h(-1) at 90 min under anaerobic condition. (C) 2021 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.

Automated summary

In this study, dopamine was efficiently synthesized using heterologous expression of dopa decarboxylase from Harmonia axyridis in Escherichia coli. The purified dopa decarboxylase was characterized and its optimal conditions for activity were determined. The feasibility of producing dopamine from L-dopa was evaluated and a fed-batch process was developed. The production of dopamine reached a high titer, yield, and productivity under anaerobic conditions.