Table 4.
Effect of different compounds on Chi18H8 activity
| Compounds | Final concentration | Relative activity (%) |
|---|---|---|
| Control | 100.0 | |
| Metal ions | mM | |
| Ca2+ | 20 | 126.8 ± 0.8 |
| Cu2+ | 20 | 0.1 |
| Fe2+ | 20 | 0.1 |
| K+ | 20 | 124.2 ± 3.1 |
| Mg2+ | 20 | 86.4 ± 1.4 |
| Mn2+ | 20 | 49.9 ± 0.1 |
| Ni2+ | 20 | 64.3 ± 0.1 |
| NH4 + | 20 | 68.0 ± 7.7 |
| Zn2+ | 20 | 16.6 ± 2.0 |
| Co2+ | 20 | 119.6 ± 1.5 |
| Chelating agents: | mM | |
| EDTA | 20 | 53.6 ± 0.1 |
| Reducing agents | mM | |
| 2-mercaptoethanol | 20 | 1.1 ± 2.1 |
| DTT | 10 | 20.5 ± 6.7 |
| Detergents | % (w/v) | |
| SDS | 1 | 0.0 |
| Triton X-100 | 1 | 72.2 ± 2.5 |
| Tween-20 | 1 | 24.0 ± 3.6 |
| DOC | 1 | 120.4 ± 0.1 |
| Nonidet P-40 | 1 | 91.0 ± 2.0 |
| NLS | 1 | 0.0 |
| Sugars | mM | |
| GlcNAc | 10 | 104.1 ± 3.3 |
| Chitobiose | 10 | 82.0 ± 1.9 |
| Organic solvents: | % (v/v) | |
| Ethanol | 10 | 90.9 ± 2.5 |
| Methanol | 10 | 88.6 ± 2.3 |
| n-Propanol | 10 | 69.4 ± 1.9 |
| DMSO | 10 | 97.7 ± 14.4 |
| Salt | M | |
| NaCl | 0.1 | 38.5 ± 1.8 |
| NaCl | 0.25 | 29.9 ± 8.1 |
| NaCl | 0.5 | 16.6 ± 0.1 |
| NaCl | 1 | 8.6 ± 0.4 |
| NaCl | 2 | 4.4 ± 2.5 |
The activity was measured by the fluorimetric assay on 4-MU-(GlcNAc)2. Activity values are reported as relative to the value of 40.7 U/mg protein (set as 100%) recorded for purified Chi18H8 at 37 °C in 100 mM sodium acetate, pH 5.0. Values represent the means of three independent experiments (mean ± standard error)