Digoxigenin (DIG) is a small hapten that can be easily conjugated via an NHS ester reaction to oligonucleotides on their 5’ or 3’ terminus. DIG can be used together with a DIG antibody as an alternative to the biotin/streptavidin system, or could be used simultaneously when a multiplexed assay is needed. This modification is also commonly used in non-radioactive immunoassays, northern/Southern blot analysis, and in situ hybridization applications.
DIG-labeled oligonucleotides are monitored with anti-DIG antibodies. The interaction between DIG and anti-DIG antibodies is very strong, thus providing a sensitive assay that can be observed directly with fluorescence. In such experiments, the antibodies are fluorescently tagged. Alternatively, the interaction can be detected indirectly; for example, using an enzyme-linked immunoassay.
To order, select DIG from the 5’ or 3’ Mods tab on the oligo order page. Note that DIG-modified oligos require HPLC purification.
Author: Jeremy Pritchard is a Technical Support Representative at IDT.