Molecular engineering of L-aspartate-α-decarboxylase for improved activity and catalytic stability.
Appl Microbiol Biotechnol
; 101(15): 6015-6021, 2017 Aug.
Article
em En
| MEDLINE
| ID: mdl-28589224
ABSTRACT
ß-Alanine is an important precursor for the production of food additives, pharmaceuticals, and nitrogen-containing chemicals. Compared with the conventional chemical routes for ß-alanine production, the biocatalytic routes using L-aspartate-α-decarboxylase (ADC) are more attractive when energy and environment are concerned. However, ADC's poorly understood properties and its inherent mechanism-based inactivation significantly limited the application of this enzyme. In this study, three genes encoding the ADC enzymes from Escherichia coli, Corynebacterium glutamicum, and Bacillus subtilis were overexpressed in E. coli. Their properties including specific activity, thermostability, and mechanism-based inactivation were characterized. The ADC enzyme from B. subtilis, which had higher specific activity and thermostability than the others, was selected for further study. In order to improve its activity and relieve its mechanism-based inactivation by molecular engineering so as to improve its catalytic stability, a high-throughput fluorometric assay of ß-alanine was developed. From a library of 4000 mutated enzymes, two variants with 18-22% higher specific activity and 29-64% higher catalytic stability were obtained. The best variant showed 50% higher ß-alanine production than the wild type after 8 h of conversion of L-aspartate, showing great potential for industrial biocatalytic production of ß-alanine.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Engenharia Genética
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Beta-Alanina
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Glutamato Descarboxilase
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article