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X-gal, X-Glu, IPTG, X-a-gal and Salmon-gal
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X-gal
Properties and Applications:
(5-bromo-4-chloro-3-indolyl-beta-D-galactoside). beta galactosidase hydrolyses X-gal forming an indigo-type
blue-green precipitate. Thus, bacteria which are positive for this enzyme produce blue colonies when grown
in the presence of X-gal.
X-gal should be dissolved in Dimethylformamide at a concentration of 20mg/ml. The stock solution should at
+4° C in the dark. Indicator plates are prepared by adding X-gal to a final concentration of 40mg/ml
(a 1:500 dilution of the stock solution) after autoclaving the agar-containing media. Further applications
of X-gal are the detection of B-Galactosidase in the fields of immunology and histochemistry.
Analytical Specifications:
Recommended storage: frozen
molecular weight: 408.64
melting point: 230° C (d)
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X-glu
Properties and Applications:
X-glu (5-bromo-4-chloro-3-indolyl-beta-D- glucuronide) is the histochemical substrate for beta-D-glucuronidase
X-glu is soluble in N,N-Dimethylformamide (DMF). Make 20mg/ml solution and store at -20° C. X-glu can be incubated
at 37° C for a few minutes to overnight at a concentration of 1-2mM substrate. Used for the visualization of E. coli
Beta-glucuronidase gene (GUS), gene fusion marker for the analysis of gene expression in transformed plants.
Analytical Specifications:
Recommended storage condition: frozen
molecular weight: 521.8
melting point: 236.8° C
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Salmon-gal
Properties and Applications:
Salmon-gal (6-Chloro-3-indolyl-β-D-galactopyranoside) is an alternative chromogenic substrate for β-galactosidase.
Salmon-gal is used in conjunction with IPTG for detection of β-galactosidase activity in bacterial colonies in a colometric assay to
detect recombinants (white) from the non-recombinants (SALMON).
Salmon-gal is cleaved at the β-1-4 bond between galactose and the 5-bromo-4-chloro-3-indolyly part of X-gal by β-galactosidase via hydrolisis.
The cleavage of Salmon-gal results in the production of a Salmon colored water insoluble pigment.
In conjunction with X-glu, salmon-gal is useful for simultaneous detection of GUS and Lac activities on the same plate.
Analytical Specifications:
Recommended Storage: 4C or below.
Solubility: DMSO and DMFO.
Protect from light and moisture.
Allow to warm to room temperature before opening.
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IPTG
(DIOXANE-FREE)
Properties and Applications:
IPTG (isopropylthio-beta-D-galactoside) is an inducer of beta-galactosidase production in bacteria.
IPTG is used together with the chromogenic substrates X-gal or Bluo-Gal to determine lac gene expression in recombinant methods.
IPTG is a chemical analog of galactose which cannot be cleaved by the enzyme B-galactosidase. Thus,
it can serve as an inducer for activity of the E. coli lac operon by binding and inactivating the lac repressor.
A stock solution, 0.1 mol/L, is prepared by dissolving IPTG in redist. water with subsequent sterile
filtration of the solution. The final concentration of IPTG in indicator plates-added after autoclaving-should b 0.2 mmol/L.
Analytical Specifications:
Recommended storage condition: frozen
Hazard warning: irritant
molecular weight: 238.21
appearance: white, free-flowing powder
melting point: 118° C
NOTE: quotes for larger sizes available upon request! email: 
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X-alpha-gal (X-a-gal)
Properties and Applications:
X-a-gal (5-Bromo-4-Chloro-3-indolyl-a-D-galactopyranoside) is a chromogenic substance used to demonstrating
a-galactosidase activity. Thus yeast S. cerevisiae which are positive for this enzyme produce blue colonies
when grown in the presence of X-a-gal. Used in yeast two-hybrid screens.
X-a-gal should be dissolved in DMF at a concentration of 2mg/ml for premade plates or 20mg/ml for indicator plates.
Analytical Specifications:
Recommended storage condition: frozen at -20° C for 6 month
Molecular weight: 408.6
Melting point: 232-234° C
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Magenta-gal
5-Bromo-6-chloro-3-indolyl-β-D-galactopyranoside
Magenta-gal
| Formula: | C14H15BrClNO6 |
| CAS: | 93863-88-8 |
| Purity: | ≥98% by TLC |
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