X-GAL

 X-GAL

X-Gal, known chemically as 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside, is a synthetic compound widely used in molecular biology as a substrate for the enzyme β-galactosidase. It is particularly useful for detecting gene expression and for identifying galactosidase-producing bacteria.

Chemical Properties

• CAS Number: 7240-90-6
• MDL Number: MFCD00005666
• EINECS: 230-640-8
• Molecular Formula: C14H15BrClNO6
• Molecular Weight: 408.63 g/mol
• Boiling Point: 673.9°C at 760 mmHg
• Melting Point: 230°C
• Flash Point: 375.9°C
• Density: 1.5563 g/cm³
• Appearance: White crystalline powder

Optical and Physical Characteristics

• Optical Rotation: -64° (c=1, H2O/DMF (1/1))
• Refractivity: Estimated at 1.6110

Storage and Handling

X-Gal should be stored at temperatures between 2°C and 8°C for long-term use, ideally in a desiccated environment to prevent degradation. It can also be stored at -20°C for extended periods. When preparing solutions, it is often dissolved in dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) to create working concentrations, typically around 20 mg/mL.

Applications

X-Gal is primarily utilized in:

• Molecular Biology: As a colorimetric substrate for β-galactosidase, X-Gal undergoes hydrolysis to produce a blue precipitate, allowing researchers to visually identify bacteria that express the lacZ gene.
• Cloning Techniques: In cloning experiments involving plasmids with lacZ genes, X-Gal helps differentiate between recombinant and non-recombinant colonies based on color change.
• Histochemistry: It serves as a histochemical substrate to detect β-galactosidase activity in various biological samples.

Safety Considerations

When handling X-Gal, appropriate personal protective equipment (PPE) such as gloves, eye protection, and respiratory protection should be used to mitigate exposure risks. The compound is not intended for direct human use and should be handled according to standard laboratory safety protocols.

In summary, X-Gal is an essential reagent in molecular biology that facilitates the detection of gene expression through its interaction with β-galactosidase, making it invaluable in research and diagnostic applications.

Citations:

1. https://www.mpbio.com/in/x-gal-molecular-biology-grade-100-mg
2. https://www.fishersci.com/shop/products/5-bromo-4-chloro-3-indolyl-d-galactopyranoside-fisher-bioreagents-2/BP1615100
3. https://www.mpbio.com/in/114063102-x-gal-powder-m-cf
4. https://www.carlroth.com/com/en/substrates-for-biochemistry/x-%CE%B2-gal/p/2315.1
5. https://en.wikipedia.org/wiki/X-gal
6. https://www.ibisci.com/products/x-gal
7. https://goldbio.com/documents/1031/Blue%20White%20Screening%20of%20Bacterial%20Colonies%20using%20X-Gal%20and%20IPTG%20Plates.pdf
8. https://www.sigmaaldrich.com/US/en/product/mm/9630op