

4-Nitrophenyl-β-D- galactosidase (p-Nitrophenyl-β-D-galactoside; PNP-β-D-Gal) by Molecular Depot is a 4-nitrophenyl-β-D-galactopyranoside, also written p-nitrophenyl-β-D-galactoside or PNP-β-D-Gal, the chromogenic substrate of β-galactosidase. β-Galactosidase releases 4-nitrophenol, which is yellow in alkali, so the reaction is followed by absorbance at about 405 nm without any further step. It is used as the substrate in colorimetric β-galactosidase assays, in lacZ reporter gene quantification and in microbial glycosidase screening. Each unit contains 1 g. MBP supplies Molecular Depot enzyme reagents to research labs in the United States, Canada and worldwide.