TY - JOUR
T1 - Purification and characterization of novel bifunctional xylanase, XynIII, isolated from Aspergillus niger A-25
AU - Chen, Hong Ge
AU - Yan, Xin
AU - Liu, Xin Yu
AU - Wang, Ming Dao
AU - Huang, Hui Min
AU - Jia, Xin Cheng
AU - Wang, Jin An
PY - 2006/7
Y1 - 2006/7
N2 - Three types of xylanases (EC 3.2.1.8) were detected in the strain Aspergillus niger A-25, one of which, designated as XynIII, also displayed β-(1,3-1,4)-glucanase (EC 3.2.1.73) activity, as determined by a zymogram analysis. XynIII was purified by ultrafiltration and ion-exchange chromatography methods. Its apparent molecular weight was about 27.9 kDa, as estimated by SDS-PAGE. The purified XynIII could hydrolyze birchwood xylan, oat spelt xylan, lichenin, and barley β-glucan, but not CMC, avicel cellulose, or soluble starch under the assay conditions in this study. The xylanase and β-(1,3-1,4)-glucanase activities of XynIII both had a similar optimal pH and pH stability, as well as a similar optimal temperature and temperature stability. Moreover, the effects of metal ions on the two enzymatic activities were also similar. The overall hydrolytic rates of XynIII in different mixtures of xylan and lichenin coincided with those calculated using the Michaelis-Menten model when assuming the two substrates were competing for the same active site in the enzyme. Accordingly, the results indicated that XynIII is a novel bifunctional enzyme and its xylanase and β-(1,3-1,4)-glucanase activities are catalyzed by the same active center.
AB - Three types of xylanases (EC 3.2.1.8) were detected in the strain Aspergillus niger A-25, one of which, designated as XynIII, also displayed β-(1,3-1,4)-glucanase (EC 3.2.1.73) activity, as determined by a zymogram analysis. XynIII was purified by ultrafiltration and ion-exchange chromatography methods. Its apparent molecular weight was about 27.9 kDa, as estimated by SDS-PAGE. The purified XynIII could hydrolyze birchwood xylan, oat spelt xylan, lichenin, and barley β-glucan, but not CMC, avicel cellulose, or soluble starch under the assay conditions in this study. The xylanase and β-(1,3-1,4)-glucanase activities of XynIII both had a similar optimal pH and pH stability, as well as a similar optimal temperature and temperature stability. Moreover, the effects of metal ions on the two enzymatic activities were also similar. The overall hydrolytic rates of XynIII in different mixtures of xylan and lichenin coincided with those calculated using the Michaelis-Menten model when assuming the two substrates were competing for the same active site in the enzyme. Accordingly, the results indicated that XynIII is a novel bifunctional enzyme and its xylanase and β-(1,3-1,4)-glucanase activities are catalyzed by the same active center.
KW - Aspergillus niger
KW - Bifunctional enzyme
KW - Purification
KW - Xylanase
KW - β-(1,3-1,4)-glucanase
UR - http://www.scopus.com/inward/record.url?scp=33746921169&partnerID=8YFLogxK
M3 - Artículo
SN - 1017-7825
VL - 16
SP - 1132
EP - 1138
JO - Journal of Microbiology and Biotechnology
JF - Journal of Microbiology and Biotechnology
IS - 7
ER -