In article <34r039$5rn at search01.news.aol.com>, gdwx at aol.com (GDWX) writes:
Dig is short for digoxigenin, a plant steroid found in foxglove.
Boehringer Mannheim produces a series of kits using this antigen as a
marker (label) which is detected using a anti-dig polyclonal produced in
sheep. However they did it, the Fab fragment is very "non-sticky". When
using biotinylated Ab or probes, there is always the difficulty of
indigenous biotin which can create background when streptavidin-enzyme
conjugates are used to detect the bioinylated marker. As long as you are
not working with foxglove (and who is) indigenous digoxigenin does not
exist.
The dig-NHS molecule I mentioned is simply activated digoxigenin, much as
biotin-NHS is used to label proteins, or more specifically, primary
amines. Alternative dig-derivatives can be used to label free SH groups.
The primary use of dig is with DNA probes, although I have successfully
used it with RNA, especially in Northern blots and in situ hybridizations.
It can also be used to label antibodies, and thus can be used in a
variety of immunoassays. Anti-dig Ab can be purchased which has alkaline
phosphatase or HRP as an enzyme label, or with a variety of fluorescent
markers.
This system is definitely worth trying. Good luck.
Dave Burden
Biotechnology Training Institute
Bridgewater, NJ
