Y‑Gal

Y‑Gal (CAS 126787‑65‑3), systematically 3‑indolyl β‑D‑galactopyranoside, is a synthetic β‑galactosidase‑specific chromogenic substrate in which a 3‑indolyl (indoxyl) aglycone is linked via a β‑glycosidic bond to D‑galactose. When hydrolyzed by β‑galactosidase (EC 3.2.1.23, LacZ) in bacterial or recombinant systems, the indoxyl moiety is released and undergoes aerial oxidation to form a yellow to brown‑colored, water‑insoluble dye, enabling clear visual detection of enzyme activity. This color distinguishes Y‑Gal from blue‑forming substrates such as X‑Gal and Bluo‑Gal, making it useful when a different chromogenic channel is required or when blue pigmentation interferes with downstream imaging. Y‑Gal is applied in recombinant‑DNA cloning for blue–white or color‑based screening of lacZ⁺ vs lacZ⁻ colonies, as well as in enzyme‑activity assays, immunohistochemistry, and reporter‑gene‑expression studies. The compound is typically soluble in aqueous or mixed aqueous‑organic buffers and is supplied as a high‑purity, research‑grade powder suitable for molecular‑biology and microbiological use.

Appearance

• Off‑white to pale yellow crystalline or lyophilized powder.
• Fine, free‑flowing texture suitable for accurate weighing and dissolution in aqueous or mixed aqueous‑organic solvents.

Source / synthesis

• Synthetically produced by coupling 3‑indoxyl with β‑D‑galactose under glycosylation conditions to form the β‑D‑galactopyranoside derivative.
• Commercially manufactured by specialty enzyme‑substrate and carbohydrate‑chemistry suppliers (e.g., Shenzhen GeneSeqTools, Hepattack, and various ChemicalBook‑linked vendors) as a high‑purity reagent.

Molecular weight and structure

• Molecular formula: C14H17NO6C14​H17​NO6​.
• Molecular weight: 295.29 g/mol.
• Structure: 1H‑indol‑3‑yl β‑D‑galactopyranoside, with a β‑glycosidic linkage between the indole C3‑O and the D‑galactose ring.

Sugar specificity

• Specifically hydrolyzed by β‑galactosidases (LacZ, EC 3.2.1.23) and other β‑galactoside‑cleaving enzymes.
• Shows minimal cross‑reactivity with α‑glycosidases under standard molecular‑biology and cloning‑medium conditions, making it suitable for selective detection of β‑galactosidase activity.

Biological activity

• Acts as a chromogenic reporter for β‑galactosidase‑mediated hydrolysis of β‑D‑galactosyl linkages in lactose analogs and glycosides.
• Enzymatic cleavage yields 3‑indoxyl, which oxidizes and dimerizes into a yellow‑to‑brown, water‑insoluble pigment, enabling sensitive detection in bacterial colonies, enzyme assays, and histochemical preparations.

Purity and microbial contamination

• Typically supplied at ≥95–99% purity as indicated by supplier data sheets (e.g., HPLC‑assayed “high‑purity raw material for scientific research”).
• Described as non‑sterile, research‑grade material with low microbial contamination status, suitable for use in standard microbiological and biochemical workflows when handled under aseptic conditions.

Identity and quality control

• Identity inferred from molecular formula, molecular weight, and spectral data (UV/Vis, NMR, and HPLC) consistent with 3‑indolyl β‑D‑galactopyranoside.
• Quality‑control checks include appearance, solubility, chromatographic purity, and performance in a defined β‑galactosidase (LacZ) activity assay on agar plates.

Shelf life and storage

• Shelf life is generally 12–24 months when stored as a dry powder at –20 °C in a tightly sealed container, protected from moisture and light.
• Stock solutions (often in DMSO, DMF, or methanol) should be prepared immediately before use or stored frozen for short periods to minimize degradation and nonspecific oxidation of the indoxyl moiety.

Application

• Color‑based or complementary selection of recombinant bacterial clones (lacZ⁺ vs lacZ⁻) on agar plates in cloning systems.
• Chromogenic β‑galactosidase assays in solution or on solid media for enzyme‑kinetic studies and activity profiling.
• Use in histochemical and cell‑based reporter‑gene assays where a yellow/brown stain is preferred over blue coloration.

Key characteristics

• Produces a yellow‑to‑brown insoluble dye upon β‑galactosidase hydrolysis, providing a spectrally distinct alternative to blue‑forming substrates.
• Defined β‑D‑galactopyranoside linkage providing selectivity for β‑galactosidases over many other glycosidases.
• Crystalline, stable powder with a known molecular formula and weight, suitable for quantitative cloning and enzyme‑assay applications.

Citations

• ChemicalBook – 3‑Indoxyl‑β‑D‑galactopyranoside (Y‑Gal, CAS 126787‑65‑3, MF C₁₄H₁₇NO₆, MW 295.29): https://www.chemicalbook.com/ChemicalProductProperty_EN_CB5713224.htm
• Hepattack – Y‑Gal product page (CAS 126787‑65‑3, 3‑indolyl β‑D‑galactopyranoside, for research): https://www.hepattack.com/en/product03_cid_215_pid_538.html
• Shenzhen GeneSeqTools – Product list entry for Y‑Gal (CAS 126787‑65‑3, alongside other chromogenic β‑galactosidase substrates): http://www.geneseqtools.com/en/product02_cid_215.html
• ChemicalBook supplier list for 126787‑65‑3 (Y‑Gal, 3‑indolyl β‑D‑galactopyranoside): https://www.chemicalbook.com/ProdSupplierGNCB8637659.htm
• 5‑Bromo‑3‑indolyl‑β‑D‑galactopyranoside (Bluo‑Gal) product page (for β‑galactosidase‑substrate context and assay principles): https://www.glpbio.com/5-bromo-3-indolyl-946-d-galactopyranoside.html
• MedChemExpress – 5‑Bromo‑3‑indolyl‑β‑D‑galactopyranoside entry (for general β‑galactosidase‑substrate overview and cloning‑use): https://www.medchemexpress.com/5-bromo-3-indolyl-%CE%B2-d-galactopyranoside.html
• IalcoPharm – 5‑Bromo‑3‑indolyl‑β‑D‑galactopyranoside information (for handling and assay‑format reference): https://www.inalcopharm.com/cart.php?m=product_detail&p=15
• abcam – Magenta‑Gal chromogenic β‑galactosidase substrate (for dye‑color and cloning‑context comparison): https://www.abcam.com/en-us/products/biochemicals/magenta-gal-chromogenic-beta-galactosidase-substrate-ab146381
• ScienceDirect – X‑Gal overview (for background on chromogenic β‑galactosidase substrates, including Y‑Gal‑class alternatives): https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/x-gal
• General glycosidase‑substrate catalog (Y‑Gal and related indolyl‑β‑D‑galactopyranosides overview): https://www.chemicalbook.com/ (search for “126787‑65‑3”)