SensoLyte® β-Galactosidase Assay Kits – Fluorimetric & Colorimetric

β -galactosidase, a widely used reporter enzyme, is used in the study of gene expression, protein-protein interactions,1 and normalization of transfection efficiency.2 β-galactosidase, enzyme encoded by the lacZ gene of E. coli, catalyzes the hydrolysis of β-galactosides into monosaccharides.

AnaSpec is pleased to announce the release of 3 new assay kits for measuring β-galactosidase activity – the SensoLyte® MUG β-Galactosidase Assay Kit (Ex/Em= 360/460 nm), SensoLyte® FDG β-Galactosidase Assay Kit (Ex/Em= 490/520 nm), and SensoLyte® ONPG β-Galactosidase Assay Kit (Abs=420 nm). One advantage of using a fluorogenic substrate, as is the case in the first two assays, is that it is possible to monitor expression in individual cells as well as analyze the heterogeneity of expression in cell populations. 3 Another major advantage is that fluorimetric assays are several times more sensitive than colorimetric assays (see Table 1).


Catalog #

SensoLyte® FDG β - Galactosidase Assay Kit *Fluorimetric* NEW


SensoLyte® MUG β - Galactosidase Assay Kit *Fluorimetric* NEW


SensoLyte® ONPG β - Galactosidase Assay Kit *Colorimetric* NEW


Table 1. Comparison of the 3 β–Galactosidase assay kits

SensoLyte® MUG
β-Galactosidase Assay

SensoLyte® FDG
β-Galactosidase Assay

SensoLyte® ONPG
β-Galactosidase Assay






Ex/Em= 360/460 nm

Ex/Em= 490/520 nm

Abs=420 nm

Substrate Used

4-Methylumbelliferyl β-D-galactopyranoside (MUG)

Fluorescein di-b-D galactopyranoside (FDG)

o-Nitrophenyl β-D-galactopyranoside (ONPG)

Hydrolysis Product

4-Methylumbelliferone (4MU)



Lowest Detection Limit

15 fg

10 pg

100 pg

Cell Lysis Requirement

With or without cell lysis3

With or without cell lysis

Cell lysis required

Figure 1. Detection of β-galactosidase activity with the SensoLyte® MUG β-Galactosidase Activity Assay Kit (A), SensoLyte® FDG β-Galactosidase Activity Assay Kit (B), and SensoLyte® ONPG β-Galactosidase Activity Assay Kit (C); with lowest detection limits at 15 fg, 10 pg and 0.1 ng, respectively.


1. Rossi, F. et al. PNAS 94, 8405 (1997).
2. Thompson CD et al. Biotechniques 27, 824 (1999).
3. Plovins, A. et al. Appl. Environ. Microbiol. 60, 4638 (1994).