A β-glucosidase (EC 18.104.22.168) 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 C. Divalent metal ions (Hg2+, Cu2+, Ca2+, Mg2+) and EDTA have negligible effect on the enzyme activity. The enzyme exhibited a high specificity on the glycon portion of aryl-β-D-glycosides. NMR spectroscopy revealed the enzyme catalyzed hydrolysis of p-nitrophenyl-β-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.
- Bronsted relationship
- Flavobacterium meningosepticum