A novel cyclodextrin glycosyltransferase from an alkalophilic Bacillus species:: purification and characterization

Cyclodextrin glycosyltransferase (E.C. 2.4.1.19) of alkalophilic Bacillus sp. 7-12 was purified by ammonium sulfate precipitation, DEAE-cellulose column chromatography and Sepharose CL-6B column chromatography. The enzyme thus obtained consisted of a single band that did not dissociate into subunits by SDS-polyacrylamide gel electrophoresis (PAGE). The molecular weight of the purified enzyme was determined to be 69,000 Da by SDS-PAGE. The enzyme was stable below 70 degreesC with an optimum activity at 60 degreesC, and was stable at a pH range of 6-10 with an optimum pH at 8.5. The enzyme activity was strongly inhibited by MgCl2, ZnCl2, CuSO4, Al-2(SO4)(3), CoCl2, AgNO3, FeSO4 and slightly inhibited by SnCl2 and MnCl2- Cal(2), KCl, EDTA and DTT had no influence on the enzyme activity. For cyclodextrin production, up to 34% conversion to cyclodextrins was obtained from 10% starch. The enzyme produced alpha-, beta- and gamma-cyclodextrins in the ratio of 0.26:1:0.86. (C) 2004 Elsevier Ltd. All rights reserved.