Cyclomaltodextrin glucanotransferase from Bacillus circulans E 192. I. Purification and characterization of the enzyme.
Biotechnol Appl Biochem
; 15(1): 48-58, 1992 Feb.
Article
em En
| MEDLINE
| ID: mdl-1532314
The cyclomaltrodextrin glucanotransferase (CGTase) [1,4-alpha-D-glucan:4-alpha-D-(1,4-alpha-D-glucano)-transferase (cyclizing), EC 2.4.1.19] from Bacillus circulans E 192 has been purified to homogeneity by Cetavlon treatment, ammonium sulfate precipitation, DEAE Trisacryl M chromatography, Q Fast Flow chromatography, and affinity on beta-cyclodextrin-Sepharose 4B. Two isoenzymes were separated by FPLC on a Mono Q column. Their isoelectric points were estimated as 6.7 and 6.9 and they represented 13 and 87%, respectively, of the initial activity. Their molecular weight, pH, and temperature optima were estimated as 78,000, 5.5, and 60 degrees C, respectively. Kinetic parameters indicated that both enzymes had the same properties; they preferentially modified high-molecular-weight substrates to produce cyclodextrins. The apparent Vmax and Km values for soluble starch were 43 mumol of beta-cyclodextrin/min/mg of protein and 0.57% (w/v), respectively. Although this CGTase is not markedly thermostable, it is protected against heat denaturation by substrate, product, and/or calcium ions. The ratios of alpha-, beta-, and gamma-cyclodextrins produced have been determined as 1/7/2 in the initial phase of the reaction and 3/3/1 at equilibrium.
Buscar no Google
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Bacillus
/
Glucosiltransferases
Idioma:
En
Revista:
Biotechnol Appl Biochem
Assunto da revista:
BIOQUIMICA
/
BIOTECNOLOGIA
Ano de publicação:
1992
Tipo de documento:
Article
País de afiliação:
França
País de publicação:
Estados Unidos