Colorimetric Label

A colorimetric label is an enzyme system in which an enzyme linked to a ligand or binder reacts with a specific substrate to generate a chromophore product. This tracer conjugate is quantified by measuring the amount of light absorbed by the product at a specific wavelength. Enzymes commonly used to label ligands or binders include alkaline phosphatase using para-nitrophenyl phosphate as substrate, horseradish peroxidase using hydrogen peroxide / coupler as substrate, and b-galactosidase using o-nitrophenyl galactoside as substrate.