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Catalogue number:
5 mg
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Fluorescein di-β-D-galactopyranoside (FDG) is one of the most sensitive fluorogenic substrates available for detecting β-galactosidase. The colorless and nonfluorescent FDG is hydrolyzed to highly fluorescent fluorescein, which exhibits excellent spectral properties (Ex/Em=492/520 nm) that match the optimal detection window of most fluorescence instruments. Galactosidase-catalyzed hydrolysis of FDG can be followed by fluorescence increase around 520 nm. Alternatively, FDG can also be used to detect β-galactosidase in a chromogenic mode since the enzymatic product (fluorescein) exhibits a large extinction coefficient (close to 100,000 cm-1mol-1). In general, fluorescence-based measurements can be several orders of magnitude more sensitive than absorption-based measurements. FDG has been widely used for identifying lacZ-positive cells with fluorescence microscopy and flow cytometry. FDG is also used to detect β-galactosidase expression in live cells. Fluorescence-based assays employing FDG are also reported to be 100 to 1000-fold more sensitive than radioisotope-based ELISAs.

Product Type:

Reagents & Kit Components

Storage Temp:

-20°C desiccated and protected from light

Compound Purity:

Minimum Purity: 95%

Molecular Weight:



Yang NC and Hu ML (2004). A fluorimetric method using fluorescein di-?-D-galactopyranoside for quantifying the senescence-associated ?-galactosidase activity in human foreskin fibroblast Hs68 cells. Anal Biochem 325, 337-43, Knapp T, et al. (2003). Detection of ?-lactamase reporter gene expression by flow cytometry. Cytometry 51A, 68-78, Nguyen DG and Hildreth JE (2003). Involvement of macrophage mannose receptor in the binding and transmission of HIV by macrophages. Eur J Immunol 33, 483-93, Poot M and Arttamangkul S (1997). Verapamil inhibition of enzymatic product efflux leads to improved detection of ?-galactosidase activity in lacZ-transfected cells. Cytometry 28, 36-41, Chung JD, et al. (1995). Flow cytometric study of differentiating cultures of Bacillus subtilis. Cytometry 20, 324-33, Ikenaka K, et al. (1990). Reliable transient promoter assay using fluorescein-di-?-D-galactopyranoside substrate. DNA Cell Biol 9, 279-86.



Reagents & Kit Components from AnaSpec: