Table 3. Biochemical characterization of novel β-galactosidases from 12AC Lac+ metagenomic clones complementing S. meliloti RmF728 (lac).
The β-galactosidase activity of purified proteins was assayed using lactose as substrate. Released glucose was quantified with a glucose oxidase activity kit.
| ORFs | Proteins | Molecular weight (kDa) | pI | Km (mM) | kcat (s-1) | kcat/Km (s-1 M-1) | Optimal tempe-rature (°C) | Optimal pH |
|---|---|---|---|---|---|---|---|---|
| Lac36W_ORF11 | β-Galactosidase (GenBank, AGW45517) | 79.6 | 8.2 | 2.5 | 10.4 | 3.7 × 103 | 42 | 6.0 |
| Lac161_ORF7 | β-Galactosidase (GenBank, AGW45552) | 109.0 | 6.7 | 1.8 | 13.2 | 7.3 × 104 | 50 | 6.0 |
| Lac161_ORF10 | β-Galactosidase (GenBank, AGW45555) | 63.7 | 9.1 | 3.2 | 8.6 | 2.7 × 103 | 37 | 6.5 |