Table 1 Substrate specificities and general properties of β-NGAs
NgaDssm | NgaCa | NgaMg | NgaAt | NgaBa | NgaBf | NgaBl | NgaLy | NgaP2 | NgaPa | |
|---|---|---|---|---|---|---|---|---|---|---|
Group 3 | Group 1 | Group 1 | Group 2 | Group 3 | Group 4 | Group 4 | Group 4 | Group 4 | GH123 | |
Substrate specificity | ||||||||||
Substrate | Relative activity (%) | |||||||||
GalNAc-β-pNP | 100 | – | – | 100 | 100 | 100 | 100 | 100 | 100 | 100 |
Galβ1-3GalNAc-β-pNP | 70.3 | 100 | – | – | 7.3 | – | – | – | – | NT |
Gal-β-pNP | – | – | – | – | – | – | – | – | – | – |
GlcNAc-β-pNP | – | – | – | 13.6 | – | – | – | – | 4.7 | – |
GalNAc-α-pNP | – | – | – | – | – | – | – | – | – | – |
GalNAc-β-4MU | 100 | – | – | 100 | 100 | 100 | 100 | 100 | 100 | 100 |
GalNAc4S-β-4MU | 183.8 | – | – | 47.9 | 1.5 | 1.9 | 2.0 | 1.3 | 29.0 | – |
GalNAc6S-β-4MU | – | – | – | – | – | – | – | – | – | – |
General property | ||||||||||
Enzyme activity | OR/MR-β-NGA | OR-β-NGA | Unknown | OR/MR-β-HEX | OR/MR-β-NGA | MR-β-NGA | MR-β-NGA | MR-β-NGA | MR-β-NGA | MR-β-NGA |
Optimal pH | 5.0 | 5.0 | – | 5.0 | 6.5 | 6.5 | 5.0 | 7.0 | 5.5 | 6.0 |
Optimal buffer | Citrate | Citrate | – | Citrate | Citrate | Citrate | Citrate | HEPES | Citrate | Acetate |
Optimal temperature (°C) | 45 | 25 | – | 40 | 70 | 35 | 45 | 40 | 40 | NT |
Tm (°C) | 63.9 | 43.1 | 70.6 | 52.9 | 93.1 | 44.3 | 57.2 | 59.7 | 56.8 | NT |
Km (mM) | (3.8 ± 0.4) | (11 ± 3) | – | (12 ± 5) | (3.9 ± 1) | (1.0 ± 0.07) | (2.8 ± 0.4) | (1.0 ± 0.05) | (0.36 ± 0.03) | 0.4 |
kcat (s−1) | (43 ± 3) | (1.2 ± 0.3) | – | (8.0 ± 3) | (510 ± 50) | (170 ± 5) | (390 ± 40) | (480 ± 10) | (28 ± 0.6) | 7.3 |
kcat/Km (s−1 mM−1) | (11) | (0.11) | – | (0.64) | (130) | (170) | (140) | (490) | (79) | 21 |
