ABSTRACT
From wild type inoculum of Bacillus circulans DF 9 which produce cyclomaltodextrin-glucanotransferase (EC 2.4.1.19, CGTase), two different kinds of colonies were isolated, which correspond to the classical S-R variation. From the culture medium of both colonies grown together a CGTase was purified about 50 fold with a yield of 54% in two steps. From pure R-cell culture the enzyme was purified by about 38 folds with a yield of 79% in only one step, showing a complete homogeneity as judged by a native PAGE analysis.
Subject(s)
Bacillus/classification , Bacillus/enzymology , Glucosyltransferases/isolation & purification , Bacillus/isolation & purification , Chromatography, Affinity , Electrophoresis, Polyacrylamide Gel , Species SpecificityABSTRACT
The cyclomaltodextrin-glucanotransferase (EC2.4.1.19, CGTase) which was purified to homogeneity from Bacillus circulans strain DF 9, R type, showed a pI of 5.3 determined by disc-isoelectric focusing, a Mw of 78 kDa estimated by SDS-PAGE with a range of pH of optimal enzymatic activity rather large (4.5-7.5). The thermal stability of the enzyme at 55 degrees C was increased 4-5 times when calcium ion (10 to 100 mM) or alpha-cyclodextrins (10 mM) were added to the preincubation mixtures. The alpha: beta: gamma ratio determined by HPLC was about 1:0.9:0.4 and the maximal conversion to cyclodextrins with 5% soluble starch was about 36%.
