E. coli β-galactosidase is a 464 kD tetramer. Each unit of β-galactosidase consists of five domains, the third of which is the active site. It is an essential enzyme in cells. Deficiencies of this enzyme can result in galactosialidosis or Morquio B syndrome. In E. coli, β-galactosidase is produced by the activation of LacZ operon. Detection of LacZ expression has become routine to the point of detection of as few as 5 copies of β-galactosidase per cell. This kit uses a chromogenic galactosidase substrate that can sensitively distinguish LacZ+ from LacZ- cells. The light yellow substate generates a strongly red product upon reaction with galactosidase. It can be used either for detecting galactosidase conjugates in ELISA type assay systems or for monitoring LacZ gene expression in cells. AmpliteColorimetric Beta-Galactosidase Assay Kit comes with all the essential components with an optimized assay protocol. It can be used for screening galactosidase inhibitors or inducers.