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A novel cyclodextrin glycosyltransferase from alkaliphilic amphibacillus sp. NPST-10 : purification and properties
Citation Link: https://doi.org/10.15480/882.1420
Publikationstyp
Journal Article
Date Issued
2012-08-22
Sprache
English
Institut
TORE-DOI
Citation
International Journal of Molecular Sciences 13 (2012), 8, S. 10505-10522
Publisher DOI
Scopus ID
Publisher
Multidisciplinary Digital Publishing Institute
Screening for cyclodextrin glycosyltransferase (CGTase)-producing alkaliphilic bacteria from samples collected from hyper saline soda lakes (Wadi Natrun Valley, Egypt), resulted in isolation of potent CGTase producing alkaliphilic bacterium, termed NPST-10. 16S rDNA sequence analysis<strong> </strong>identified the isolate as <em>Amphibacillus</em><em> </em>sp. CGTase was purified to homogeneity up to 22.1 fold by starch adsorption and anion exchange chromatography with a yield of 44.7%. The purified enzyme was a monomeric protein with an estimated molecular weight of 92 kDa using SDS-PAGE. Catalytic activities of the enzyme were found to be 88.8 U mg<sup>−1</sup> protein, 20.0 U mg<sup>−1</sup> protein and 11.0 U mg<sup>−1</sup> protein for cyclization, coupling and hydrolytic activities, respectively. The enzyme was stable over a wide pH range from pH 5.0 to 11.0, with a maximal activity at pH 8.0. CGTase exhibited activity over a wide temperature range from 45 °C to 70 °C, with maximal activity at 50 °C and was stable at 30 °C to 55 °C for at least 1 h. Thermal stability of the purified enzyme could be significantly improved in the presence of CaCl<sub>2</sub>. <em>K</em><sub>m</sub> and <em>V</em><sub>max</sub> values were estimated using soluble starch as a substrate to be 1.7 ± 0.15 mg/mL and 100 ± 2.0 μmol/min, respectively. CGTase was significantly inhibited in the presence of Co<sup>2+</sup>, Zn<sup>2+</sup>, Cu<sup>2+</sup>, Hg<sup>2+</sup>, Ba<sup>2+</sup>, Cd<sup>2+</sup>, and 2-mercaptoethanol. To the best of our knowledge, this is the first report of CGTase production by <em>Amphibacillus</em> sp. The achieved high conversion of insoluble raw corn starch into cyclodextrins (67.2%) with production of mainly β-CD (86.4%), makes <em>Amphibacillus</em> sp. NPST-10 desirable for the cyclodextrin production industry.
DDC Class
570: Biowissenschaften, Biologie
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