| Bioactivity | ONPG is a colorimetric and spectrophotometric substrate for detection of β-galactosidase activity. | ||||||||||||
| Invitro | The enzyme displays high hydrolysis ability for ONPG (100%) and moderate activity for its natural substrate lactose (25.7%). However, the hydrolysis ability of the enzyme towards all other chromogenic nitrophenyl analogues is very weak, indicating that Gal308 is a β-galactosidase with narrow substrate specificity. To investigate the kinetic parameters of recombinant enzyme, the Michaelis-Menten constants (Km), turnover numbers (kcat), and catalytic efficiencies (kcat/Km) of Gal308 for ONPG and lactose are determined. The kcat and Km values are 464.7±7.8 s-1 and 2.7±0.3 mM for ONPG, and 264.2±2.1 s-1 and 7.1±0.8 mM for lactose, respectively. The kcat/Km value of the enzyme for ONPG (172.1 s-1mM-1) is 4.6-fold higher than that for lactose (37.2 s-1mM-1), which clearly demonstrated that the catalytic efficiency of Gal308 for ONPG is much higher than that for lactose[1]. | ||||||||||||
| Name | ONPG | ||||||||||||
| CAS | 369-07-3 | ||||||||||||
| Formula | C12H15NO8 | ||||||||||||
| Molar Mass | 301.25 | ||||||||||||
| Appearance | Solid | ||||||||||||
| Transport | Room temperature in continental US; may vary elsewhere. | ||||||||||||
| Storage |
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| Reference | [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. doi: 10.1186/1471-2180-13-237. |