Purification and properties of an exo-(1-->3)-beta-D-galactanase from Aspergillus niger.
Carbohydr Res
; 264(2): 281-91, 1994 Nov 15.
Article
em En
| MEDLINE
| ID: mdl-7805066
ABSTRACT
An exo-(1-->3)-beta-D-galactanase was purified by six chromatographic steps from a culture supernatant of Aspergillus niger. Its apparent molecular mass was 66 kDa, as estimated by SDS-PAGE analysis. The purified enzyme had no detectable activity on various p-nitrophenyl glycosides and on native plant polysaccharides but exhibited a high activity on a (1-->3)-beta-D-linked galactan backbone obtained after partial acid hydrolysis and two Smith degradations of gum arabic. The optimum conditions were pH 4.5 and 40-50 degrees C. The enzyme had a Michaelis constant (Km) of 1.9 mg/mL for the beta-(1-->3)-D-galactan with a maximum reaction velocity (Vmax) of 1380 nkat/mg. The study of the reaction products obtained after enzyme treatment of two galactans derived from gum arabic through one or two Smith degradations showed that it was an exo-(1-->3)-beta-D-galactanase able to by-pass the branching points of galactan backbones and thus to release the side-chains of type II arabinogalactans in an undegraded form.
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Base de dados:
MEDLINE
Assunto principal:
Aspergillus niger
/
Beta-Galactosidase
Idioma:
En
Ano de publicação:
1994
Tipo de documento:
Article