[35S]-labeled oligonucleotides

Michael L. Sullivan mlsulliv at facstaff.wisc.edu
Fri Jun 11 09:03:04 EST 2004

>I've a [35S]-labeled oligonucleotide. In the data sheet its mentioned that
>the labeling is made on the G* (Guanidine) and T* (Thimidine). If I look at
>the chemical structure of these compounds, there's no Sulpher (S)
>Who can tell me how they still can label those compounds with [35S]?

Probably one of the oxygens on the phosphate group is replaced with a 
labeled sulfer.  When lots of sequencing was done by hand with 
radioactivity, S-35 labeled nucleotides were very often used because 
their lower energy emission gave better clarity on gels, and the 
longer half life gave the labeled nucleotide a good shelf life 
relative to the P-32 counterparts.


Michael L. Sullivan, Ph.D
Research Plant Molecular 
U.S. Dairy Forage Research Center
1925 Linden Drive West
Madison WI, 53706

(608) 264-5397 Phone
(608) 264-5147 Fax

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