Digoxigenin


Digoxigenin is a steroid found exclusively in the flowers and leaves of the plants Digitalis purpurea, Digitalis orientalis and Digitalis lanata, where it is attached to sugars, to form the glycosides.

Use in biotechnology

Digoxigenin is a hapten, a small molecule with high antigenicity, that is used in many molecular biology applications similarly to other popular haptens such as 2,4-Dinitrophenol, biotin, and fluorescein. Typically, digoxigenin is introduced chemically into biomolecules to be detected in further assays.
DIG-binding proteins. Tinberg et al. designed artificial proteins that bind DIG. Their best binder, DIG10.3, was a 141 amino acid protein that bound DIG with a dissociation constant of 541 pM.
Anti-digoxigenin antibodies with high affinities and specificity are used in a variety of biological immuno-assays. The antibodies are labeled with dyes, enzymes or fluorescence, directly or secondarily, for visualization and detection.
Digoxigenin is thus an all-purpose immuno-tag, and in particular a standard immunohistochemical marker for in situ hybridization. In this case it is conjugated to a single species of RNA nucleoside triphosphate, which is then incorporated into RNA as it is synthesized by the cellular machinery.
It allows to make :