5-Bromo-3-indolyl-beta-D-galactopyranoside
[CAS# 97753-82-7]

Identification

• Classification: Biochemical >> Carbohydrate >> Monosaccharide
• Name: 5-Bromo-3-indolyl-beta-D-galactopyranoside
• Synonyms: (2S,3R,4S,5R,6R)-2-[(5-bromo-1H-indol-3-yl)oxy]-6-(hydroxymethyl)oxane-3,4,5-triol
• Molecular Formula: C₁₄H₁₆BrNO₆
• Molecular Weight: 374.18
• CAS Registry Number: 97753-82-7
• SMILES: C1=CC2=C(C=C1Br)C(=CN2)O[C@H]3[C@@H]([C@H]([C@H]([C@H](O3)CO)O)O)O

Properties

• Density: 1.8±0.1 g/cm³ Calc.^*
• Boiling point: 646.6±55.0 °C 760 mmHg (Calc.)^*
• Flash point: 344.9±31.5 °C (Calc.)^*
• Index of refraction: 1.731 (Calc.)^*
• alpha: -34.5 ° (c=1% in DMF/H2O 1:1)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319
• Safety Statements: P501-P270-P264-P280-P302+P352-P337+P313-P305+P351+P338-P362+P364-P332+P313-P301+P312+P330

Discovery and Applications

5-Bromo-3-indolyl-beta-D-galactopyranoside is a synthetic chemical compound primarily used as a chromogenic substrate for detecting the enzyme beta-galactosidase activity. Structurally, it consists of a 5-bromo-3-indolyl group linked to a beta-D-galactopyranoside sugar moiety through a glycosidic bond. When beta-galactosidase cleaves this bond, it releases 5-bromo-3-indoxyl, which subsequently undergoes oxidation and dimerization to form an intensely colored insoluble product, often a blue or indigo precipitate.

The use of 5-bromo-3-indolyl-beta-D-galactopyranoside as a substrate stems from the need for sensitive and visually detectable methods to measure beta-galactosidase activity. Beta-galactosidase is an enzyme widely utilized in molecular biology, especially as a reporter enzyme in gene expression studies involving the lacZ gene. This substrate enables researchers to identify and localize cells or colonies expressing beta-galactosidase by the development of a colored product, facilitating screening and selection processes.

The discovery of this substrate was part of the broader development of chromogenic compounds to provide a straightforward and effective visual assay. Its ability to produce a distinct and stable color change upon enzymatic action has made it a preferred choice in bacterial and cell biology laboratories. It is commonly used in blue-white screening techniques, which distinguish between recombinant and non-recombinant bacterial colonies by the presence or absence of color development when grown on media containing this substrate.

In addition to its application in molecular cloning, 5-bromo-3-indolyl-beta-D-galactopyranoside is used in microbial identification and quantification. Many bacterial species express beta-galactosidase, and the substrate facilitates rapid detection of these organisms through the formation of a colored product. This application is especially valuable in clinical microbiology and environmental monitoring.

The substrate is also applied in enzymology to study beta-galactosidase activity, including enzyme kinetics, inhibitor screening, and assessment of enzyme stability under various conditions. The visual nature of the assay simplifies qualitative and semi-quantitative measurements, although more precise quantification can be achieved by coupling the substrate with spectrophotometric methods.

Synthesis of 5-bromo-3-indolyl-beta-D-galactopyranoside involves chemical methods to attach the galactopyranoside sugar to the 5-bromo-3-indolyl moiety. The resulting compound is supplied as a stable powder or solution suitable for laboratory use. Proper storage conditions are necessary to maintain substrate integrity and assay reliability.

Safety protocols for handling this compound align with standard laboratory practices, including use of personal protective equipment and appropriate disposal measures to prevent environmental contamination.

Overall, 5-bromo-3-indolyl-beta-D-galactopyranoside serves as an essential reagent in biotechnology and microbiology, enabling efficient detection and analysis of beta-galactosidase activity through a visually accessible colorimetric assay. Its established applications continue to support genetic, enzymatic, and microbiological research and diagnostic procedures.

References

1987. [Determination of beta-galactosidase activity on nitrocellulose plates using 5-bromo-3-indolyl-beta-D-galactopyranoside and tetrazolium salts]. Bioorganicheskaia khimiia, 13(2).
URL: https://pubmed.ncbi.nlm.nih.gov/3107576

1995. Evaluation of new medium with chromogenic substrates for members of the family Enterobacteriaceae in urine samples. Journal of Clinical Microbiology, 33(1).
DOI: 10.1128/jcm.33.1.199-201.1995