In response to your query:
>Does anyone have any experience with MALDI-MS of phosphothioate
>oligonucleotides? I obtain reasonable spectra for phosphodiester oligos but
>I have no luck with the phosphothioates.
I have done some MALDI of phosphorothioate containing RNAs. We generally
use 3-HPA as our matrix with ammonium citrate buffer (pH 9). Pretty
standard conditions. In my hands, the phosphorothioates fly just about as
well as the unmodified RNAs. The longest phosphorothioate containing oligo
that I studied was 15 or 18 nucleotides. I seem to recall a graduate
student in one of the other labs here also successfully used our conditions
on oligos containing phosphorodithioates. Do you have specific questions
regarding our conditions? I'll be glad to help if I can.
Sincerely,
Andrew Feig
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Andrew Feig
Department of Chemistry and Biochemistry
University of Colorado at Boulder
Campus Box 215
Boulder, CO 80309
phone: (303) 492-8536
fax: (303) 492-3586
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