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- Title
Synthesis and radioiodination of a stannyl oligodeoxyribonucleotide.
- Authors
Dougan, H; Hobbs, J B; Weitz, J I; Lyster, D M
- Abstract
Synthesis and radioiodination of a stannyl oligodeoxyribonucleotide were undertaken to evaluate a gamma ray emitting ODN ligand for thrombus imaging in vivo . Synthesis of the ODN was based on modified automatedbeta-cyanoethyl phosphoramidite chemistry with an organotin nucleoside (dU*) coupled to a thrombin binding aptamer sequence to give d(U*GGTTGGTGTGGTTGG). The synthesis accommodated dU*, which is destannylated by iodine or acids. Fourteen standard synthesis cycles were followed by one 'stannyl synthesis cycle', distinguished by Fmoc protection, omission of capping, oxidation by an organic peroxide and cleavage by ammonium hydroxide. The organotin nucleoside phosphoramidite {5'-[fluorenylmethoxycarbonyl]-5-(E)-[2-tri-n -butylstannylvinyl]-2'-deoxyuridine-3'-(2-cyanoethyl N,N-diisopropyl phosphoramidite)} was prepared from 5-iodo-2'-deoxyuridine. A customized mild rapid workup included deprotection with methylamine, and reverse phase HPLC with CH3CN/triethylammonium bicarbonate. Pure stannyl ODN was highly retained by reverse phase HPLC. Radioiodination of stannyl ODN (100 microg) provided 123I-labeling yields up to 97%. Five alternative oxidants were effective. High specific activity [123I]- ODN (15 000 Ci/mmol) was recovered, separated from unlabeled isomers. Excellent reverse phase HPLC resolution of ODN isomers (alternatively I, Cl, H or Br in vinyl deoxyuridine) was essential. The affinity of the iodovinyl aptamer analog (Kd = 36 nM) for human alpha-thrombin was similar to the native aptamer (Kd = 45 nM).
- Publication
Nucleic acids research, 1997, Vol 25, Issue 14, p2897
- ISSN
0305-1048
- Publication type
Journal Article
- DOI
10.1093/nar/25.14.2897