Title: X-gal
CAS Registry Number: 7240-90-6
CAS Name: 5-Bromo-4-chloro-1
H-indol-3-yl b-D-galactopyranoside
Molecular Formula: C14H15BrClNO6
Molecular Weight: 408.63
Percent Composition: C 41.15%, H 3.70%, Br 19.55%, Cl 8.68%, N 3.43%, O 23.49%
Literature References: Chromogenic substrate of the
lacZ gene product, b-galactosidase; produces a rich blue color when cleaved by the enzyme. Prepn: J. P. Horwitz
et al., J. Med. Chem. 7, 574 (1964). Colorimetric reaction in tissue to localize b-galactosidase: B. Pearson
et al., Lab. Invest. 12, 1249 (1963); Z. Lojda,
Histochemie 23, 266 (1970). Protocol for blue-white a-complementation screening: J. Sambrook
et al., Molecular Cloning: A Laboratory Manual (Cold Spring Harbor, New York, 2nd ed., 1989) pp 1.7-1.9, 1.85-1.87. Optimization of detection of exogenous bacterial
lacZ expression: D. J. Weiss
et al., Hum. Gene Ther. 8, 1545 (1997); of fixative conditions in X-gal staining: W. Ma
et al., J. Histochem. Cytochem. 50, 1421 (2002); of blue-white screening procedure: A. L. Sherwood,
BioTechniques 34, 644 (2003).
Properties: Amorphous solid from methanol, mp 237-239° (dec). [a]D24 -69° (c = 1.0 in 50% DMF). Sol in DMF, DMSO.
Melting point: mp 237-239° (dec)
Optical Rotation: [a]D24 -69° (c = 1.0 in 50% DMF)
Use: In histochemical staining, in blue-white selection of bacterial colonies with
lacZ gene activity during cloning experiments.
