L-aspartate-β-decarboxylase (Asd) catalyzes the decarboxylation of L-aspartic acid to produce L-alanine. The enzymatic properties of the Asd enzyme derived from Acinetobacter radioresistens were analyzed to provide a reference for industrial production of L-alanine. The expression plasmid pET28a-ArAsd was constructed and transformed into E. coli BL21 (DE3) to achieve heterologous expression of the ArAsd gene. After purification by affinity chromatography to obtain a pure enzyme carrying the His-tag, the enzymatic properties were studied. And the tolerances of the recombinant bacteria to substrates and products were investigated. The results showed that the specific enzyme activity of the recombinant enzyme was 753 U/mg, and its optimum catalytic temperature and reaction pH were 55 ℃ and 4.5, respectively. It was stable under the condition of 40-45 ℃ and pH 6.0-7.0. The enzyme maintained 70% activity after treated at 45 ℃ for 3 h, and maintained 90% activity after treated at pH 7.0 for 12 h. When the concentration of the product L-alanine exceeded 500 mmol/L, the activity of the recombinant cells was significantly reduced, and the substrate L-aspartic acid could promote the catalytic activity of the recombinant cells. The Asd derived from Acinetobacter radioresistens was expressed in E. coli for the first time. The activity of ArAsd is the highest to date, and it has great potential for the industrial production of L-alanine.
YU Jiayin
,
ZHAO Ting
,
LIU Zhongmei
,
ZHOU Li
,
ZHOU Zhemin
. Expression and characterization of L-aspartate β-decarboxylase from Acinetobacter radioresistens[J]. Food and Fermentation Industries, 2020
, 46(12)
: 8
-13
.
DOI: 10.13995/j.cnki.11-1802/ts.023070
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