ONPG

Names

[ CAS No. ]:
369-07-3

[ Name ]:
ONPG

[Synonym ]:
EINECS 206-716-1
2-Nitrophenyl β-D-galactopyranoside
T6OTJ BOR BNW& CQ DQ EQ F1Q &&β-D-Galacto Form
MFCD00063255
2-Nitrophenyl β-D-Galactopyranoside [Substrate
o-Nitrophenyl β-D-galactopyranoside
β-D-Galactopyranoside, 2-nitrophenyl
2-Nitrophenyl β-D-galactoside
2-Nitrophenyl beta-D-Galactopyranoside
2-Nitrophenyl β-D-galactopyranoside (ONPG)
2-Nitrophenyl-β-D-galactopyranoside
ortho-Nitrophenyl-β-galactoside
ONPG

Biological Activity

[Description]:

ONPG is a colorimetric and spectrophotometric substrate for detection of β-galactosidase activity.

[Related Catalog]:

Signaling Pathways >> Others >> Others

Biochemical Assay Reagents

Research Areas >> Others

[In Vitro]

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].

[Kinase Assay]

The β-galactosidase activity is measured using two substrates including ONPG and lactose in this study. The β-galactosidase activity for ONPG is measured by following the amount o-nitrophenol released from ONPG. The reaction mixture is composed of 100 μL of the enzyme solution and 400 μL of ONPG solution (2.5 g/L in 100 mM Tris-HCl buffer at pH 6.8). After incubation at 78°C for 15 min, the reaction is terminated by adding an equal volume of 1 M Na2CO3. The released o-nitrophenol is quantitatively determined by measuring at A405. One unit of activity is defined as the amount of enzyme needed to produce 1 μmol of o-nitrophenol per minute under the assay condition. The specific activity is expressed as units per milligram of protein. Assays for activity towards lactose are performed in the same buffer containing 100 μL of enzyme solution and 5% lactose, and the reaction is stopped by boiling for 10 min, and the concentration of glucose is determined using a glucose oxidase-peroxidase assay kit. The released glucose is quantitatively determined by measuring A492. One unit of enzyme activity is defined as the amount of activity required to release 1 μmol of glucose per minute[1].

[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. doi: 10.1186/1471-2180-13-237.

[Related Small Molecules]

Chemical & Physical Properties

[ Density]:
1.6±0.1 g/cm3

[ Boiling Point ]:
572.4±50.0 °C at 760 mmHg

[ Melting Point ]:
186-193 °C (dec.)

[ Molecular Formula ]:
C₁₂H₁₅NO₈

[ Molecular Weight ]:
301.249

[ Flash Point ]:
300.0±30.1 °C

[ Exact Mass ]:
301.079773

[ PSA ]:
145.20000

[ LogP ]:
-0.78

[ Vapour Pressure ]:
0.0±1.7 mmHg at 25°C

[ Index of Refraction ]:
1.648

[ Storage condition ]:
2~8°C

MSDS

Click to get detail MSDS

Safety Information

[ Personal Protective Equipment ]:
Eyeshields;Gloves;type N95 (US);type P1 (EN143) respirator filter

[ Hazard Codes ]:
Xi

[ Risk Phrases ]:
R36/37/38

[ Safety Phrases ]:
S22-S24/25

[ RIDADR ]:
NONH for all modes of transport

[ WGK Germany ]:
3

[ HS Code ]:
29400090

Precursor & DownStream

Precursor

DownStream

Customs

[ HS Code ]: 29400090

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