Properties of a beta-D-mannosidase from Aspergillus niger.
Biochim Biophys Acta
; 522(2): 521-30, 1978 Feb 10.
Article
em En
| MEDLINE
| ID: mdl-623772
ABSTRACT
The beta-D-mannosidase (beta-D-mannoside mannohydrolase, EC 3.2.1.25) from culture filtrate of Aspergillus niger has been purified in large amounts by fractionation with (NH4)2SO4 and DEAE-cellulose chromatography. The removal of traces of alpha-D-galactosidase was performed on a Sepharose-epsilon-aminocaproyl-galactosylamine column. The final enzyme preparation (specific activity 188 units) has no other glycosidase activity and is judged homogeneous. The enzyme has a molecular weight of 130 000 +/- 5000 and an isoelectric point of 4.7. The amino acid composition of the enzyme is characterized by high proportion of acidic amino acids and no cysteine residues and a single chain structure of the enzyme is suggested. The enzyme shows maximum activity on p-nitrophenyl-beta-D-mannopyrano-side at pH 3.5 and at 55 degrees C. The presence of 80% of beta-sheet structure in the protein and 20.8% of monosaccharides (Gal 1.3; Man 7; GlcNAc 1) could explain this relative high heat stability (up to 2 h at 55 degrees C). Enzyme activity is inhibited by mannose (Ki = 7.85 mM) and the specificity is examined.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Aspergillus niger
/
Manosidases
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
1978
Tipo de documento:
Article