[Characterization and molecular modification of ß-glucosidase from Citrobacter koser GXW-1].
Wei Sheng Wu Xue Bao
; 57(3): 363-74, 2017 Mar 04.
Article
em Zh
| MEDLINE
| ID: mdl-29756435
ABSTRACT
Objective:
The aim of this study was to characterize ß-glucosidase from Citrobacter koser GXW-1 isolated from soil and to improve the enzyme by molecular modification. Mehods A bacterial strain with ß-glucosidase activity was screened from the soil around Wuming sugar mill in Guangxi by esculin-ferric ammonium citrate selecting plate. The 16S rDNA of the strain was obtained and analyzed. By searching GenBank database, the genes encoding ß-glucosidase from the same genus Citrobacter were found. These sequences were aligned. Then, a gene encoding ß-glucosidase was amplified by PCR. The recombinant plasmid pQE-cbgl was constructed. The recombinant protein was purified with Ni-NTA. The enzyme properties of the recombinant protein CBGL were studied in detail. At last, the wild enzyme CBGL was reformed by error-prone PCR and site-directed random mutagenesis.Results:
C. koser GXW-1 with ß-glucosidase activity was isolated from the soil. A gene encoding ß-glucosidase was cloned from the wild strain GXW-1. The properties of CBGL were identified. Its optimal pH and temperature were 6.0 and 45â. Its Km and Vmax value were (11.280±1.073) mmol/L and (0.1704±0.0073) µmol/(mg·min), respectively. Its Ki values was (66.84±3.40) mmol/L. CBGL can hydrolyze α-pNPG, stevioside, daidzin and genistin. CBGL was modified by error-prone PCR and site directed random mutagenesis. A positive mutant W147F was obtained successfully. Its Vmax was 2.54 times that of the wild enzyme CBGL.Conclusion:
CBGL not only can hydrolyze ß-glycosidic bond, but also can hydrolyze the α-glycosidic bond in α-pNPG. Furthermore, CBGL can hydrolyze stevioside, daidzin and genistin. These characteristics indicate that the ß-glucosidase CBGL has important applications in theoretical research and in industry.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
/
Citrobacter
/
Beta-Glucosidase
Tipo de estudo:
Prognostic_studies
Idioma:
Zh
Ano de publicação:
2017
Tipo de documento:
Article