o-Nitrophenyl-á-D-Galactopyranoside, 25g

o-Nitrophenyl-β-D-galactoside (ONPG) is a colorimetric substrate for b-galactosidase. This product is hydrolyzed to o-nitrophenol by the enzyme. o-Nitrophenol is yellow in alkaline solution and can be quantitated at 410-420 nm 2 . o-Nitrophenyl-β-D-galactoside is a cell culture component for molecular genetics. It is chromogenic substrate for b-galactosidase and hence is useful in the detection of lacZ activity. β-galactosidase, breaks down lactose into galactose and glucose. β-Galactosidase is not lactose specific and can act on simple galactosides. 2-Nitrophenyl β-D-galactopyranoside hydrolysis results in the release of galactose and a yellow chromogenic compound. The test substrate does not depend on an induced or constitutive permease enzyme to enter the cell, therefore reactions are rapid and occur within a 24-hour period.