%0 Journal Article
%T A Novel Cyclodextrin Glycosyltransferase from Alkaliphilic Amphibacillus sp. NPST-10: Purification and Properties
%A Abdelnasser S. S. Ibrahim
%A Ali A. Al-Salamah
%A Mohamed A. El-Tayeb
%A Yahya B. El-Badawi
%A Garabed Antranikian
%J International Journal of Molecular Sciences
%D 2012
%I MDPI AG
%R 10.3390/ijms130810505
%X 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 identified the isolate as Amphibacillus 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 £¿1 protein, 20.0 U mg £¿1 protein and 11.0 U mg £¿1 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£¿¡ãC to 70£¿¡ãC, with maximal activity at 50£¿¡ãC and was stable at 30£¿¡ãC to 55£¿¡ãC for at least 1 h. Thermal stability of the purified enzyme could be significantly improved in the presence of CaCl 2. K m and V max values were estimated using soluble starch as a substrate to be 1.7 ¡À 0.15 mg/mL and 100 ¡À 2.0 ¦Ìmol/min, respectively. CGTase was significantly inhibited in the presence of Co 2+, Zn 2+, Cu 2+, Hg 2+, Ba 2+, Cd 2+, and 2-mercaptoethanol. To the best of our knowledge, this is the first report of CGTase production by Amphibacillus sp. The achieved high conversion of insoluble raw corn starch into cyclodextrins (67.2%) with production of mainly ¦Â-CD (86.4%), makes Amphibacillus sp. NPST-10 desirable for the cyclodextrin production industry.
%K alkaliphiles
%K soda lakes
%K cyclodextrin glycosyltransferase
%K Amphibacillus sp.
%K purification
%K 16S rDNA
%U http://www.mdpi.com/1422-0067/13/8/10505