o-Nitrophenyl β-D-galactopyranoside (ONPG)

o-Nitrophenyl β-D-galactopyranoside (ONPG)

$29.00
Weight

o-Nitrophenyl β-D-galactopyranoside (ONPG)

Chromogenic Substrate for β-Galactosidase Activity Assays

Catalog Number: ASC-1022
CAS Number: 369-07-3
Molecular Formula: C₁₂H₁₅NO₈
Molecular Weight: 301.2 g/mol

Overview

o-Nitrophenyl β-D-galactopyranoside (ONPG) is a chromogenic substrate widely used for the quantitative measurement and kinetic analysis of β-galactosidase (lacZ) enzyme activity. It is a standard reagent in molecular biology, microbiology, and diagnostic microbiology.

ONPG is hydrolysed by β-galactosidase to yield galactose and o-nitrophenol, a yellow chromophore that can be readily quantified by spectrophotometry. Unlike lactose, ONPG does not require β-galactoside permease to enter the cell, making it particularly useful for enzyme assays in permease-deficient strains.

Ausamics ONPG is supplied with consistent purity and reliable performance, suitable for routine and research laboratory applications.

Key Features & Benefits

  • Chromogenic substrate for β-galactosidase detection

  • Produces yellow o-nitrophenol upon enzymatic hydrolysis

  • Enables quantitative and kinetic enzyme assays

  • Does not require lactose permease for cellular uptake

  • Widely used in lacZ reporter gene and diagnostic assays

Typical Applications

Molecular Biology & Genetics

  • Measurement of β-galactosidase (lacZ) reporter gene activity

  • Quantitative enzyme kinetics studies

  • Gene expression and promoter analysis

Microbiology & Diagnostics

  • Detection of lactose-fermenting Enterobacteriaceae

  • Differentiation of β-galactosidase-positive bacteria

  • Enzyme activity screening in bacterial cultures

Research & Teaching Laboratories

  • Demonstration of chromogenic enzyme reactions

  • Enzyme assay method development

  • Microbial physiology studies

Principle of the Substrate

β-Galactosidase catalyses the hydrolysis of ONPG into galactose and o-nitrophenol. The released o-nitrophenol produces a yellow colour that can be measured spectrophotometrically, typically at 420 nm, providing a direct and quantitative measure of enzyme activity.

Because ONPG enters cells independently of β-galactoside permease, it allows accurate assessment of β-galactosidase activity even in permease-negative strains.

Physical & Chemical Properties

  • Appearance: White to off-white crystalline powder

  • Solubility: Soluble in water

  • Chromogenic reaction: Colourless → yellow upon hydrolysis

  • Stability: Stable under recommended storage conditions

Storage & Stability

  • Store at 2–8 °C or 15–25 °C as specified on the label

  • Protect from moisture and light

  • Keep container tightly closed

  • Use before the stated expiry date

Intended Use

For laboratory research use only.
Not for human or animal use.
Not for food, feed, or pharmaceutical applications.

Quality & Compliance

  • Suitable for molecular biology and microbiology research

  • Supplied with Certificate of Analysis (COA)

  • SDS available upon request

  • Consistent batch-to-batch performance

Customs & Trade Information

HS / AHECC Code: 2932.99.00
Heterocyclic organic compounds

Why Buy ONPG from Ausamics?

Ausamics is an Australian life-science supplier specialising in enzymes, substrates, dyes, and microbiological reagents, offering:

  • Reliable local supply

  • Consistent quality and documentation

  • Competitive research pricing

  • Responsive technical support

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