| Description | ONPG (2-Nitrophenyl β-D-galactopyranoside) is a colorimetric and spectrophotometric substrate used to detect β-galactosidase activity. |
| In vitro | 该酶对ONPG的水解能力极高（100%），对其天然底物乳糖的活性中等（25.7%）。然而，该酶对所有其他的含硝基苯基类似物的水解能力非常弱，表明Gal308是一种底物特异性狭窄的β-半乳糖苷酶。为了研究重组酶的动力学参数，测定了Gal308对ONPG和乳糖的迈克利斯-莫滕常数（Km）、转化数（kcat）和催化效率（kcat/Km）。对于ONPG，kcat和Km值分别为464.7±7.8 s^-1和2.7±0.3 mM；对于乳糖，相应值为264.2±2.1 s^-1和7.1±0.8 mM。酶对ONPG的kcat/Km值（172.1 s^-1mM^-1）是对乳糖的4.6倍（37.2 s^-1mM^-1），明显展示了Gal308对ONPG的催化效率远高于对乳糖。 |
| Target activity | β-gal:2.7±0.3 mM(Km), β-gal:464.7±7.8/s(kcat) |
| Synonyms | 2-硝基苯-beta-D-半乳糖苷, 2-Nitrophenyl β-D-galactopyranoside |
| molecular weight | 301.25 |
| Molecular formula | C12H15NO8 |
| CAS | 369-07-3 |
| Storage | store at low temperature | Powder: -20°C for 3 years | In solvent: -80°C for 1 year | Shipping with blue ice. |
| Solubility | H2O: 7.4 mg/mL (24.56 mM), Sonication is recommended. |
| References | 1. Zhang X, et al. Metagenomic approach for the isolation of a thermostable β-galactosidase with high tolerance of galactose and glucose from soil samples of Turpan Basin. BMC Microbiol. 2013 Oct 24;13:237. |