- 作者: 李耀坤 ; 邱惜禾 ; 宋郁慧
- 作者服務機構: 交通大學應用化學系
- 中文摘要: A .beta.-glucosidase (EC 3.2.1.21) from Flavobacterium meningosepticum has been purified and characterized. Purity was enhanced at least 530-fold from crude cell extract with 16.6% yield. The estimated molecular mass of the purified enzyme is 150 kDa by gel filtration and 78 kDa by SDS-PAGE. This dimeric enzyme has a pI=9.0 and an optimal activity at pH 5.0 and temperature of 50.degree.C. Divalent metal ions (Hg/sup 2+/, Cu/sup 2+/, Ca/sup 2+/, Mg/sup 2+/) and EDTA have negligible effect on the enzyme activity. The enzyme exhibited a high specificity on the glycon portion of aryl-.beta.-D-glycosides. NMR spectroscopy revealed the enzyme catalyzed hydrolysis of P-nitrophenyl-.beta.-D-glucopyranoside with the retention of anomeric configuration, indicating that a double displacement mechanism was involved. A preliminary study of the Bronsted relationship showed a concave-downward plot, which is consistent with the two-step mechanism.
- 英文摘要: --
- 中文關鍵字: Flavobacterium; Purification; Bronsted Relationship; Glucosidase
- 英文關鍵字: 黃菌;純化;布倫斯關係;葡萄糖