Phosphorothioate-modified oligodeoxyribonucleotides. III. NMR and UV spectroscoptc studies of theRp-Rp,Sp-Sp, andRp-Spduplexes, [d(GGsAATTCC)]2, derived from diastereomericO-ethyl phosphorothioates | Zendy

Laurine A. LaPlanche | Zendy; Thomas Leroy James | Zendy; Cindy Powell | Zendy; W. David Wilson | Zendy; Bogdan Uznański | Zendy; Wojciech J. Stec | Zendy; Michael F. Summers | Zendy; Gerald Zon | Zendy

Open Access

Phosphorothioate-modified oligodeoxyribonucleotides. III. NMR and UV spectroscoptc studies of theR_p-R_p,S_p-S_p, andR_p-S_pduplexes, [d(GG_sAATTCC)]₂, derived from diastereomericO-ethyl phosphorothioates

Author(s) -

Laurine A. LaPlanche,

Thomas Leroy James,

Cindy Powell,

W. David Wilson,

Bogdan Uznański,

Wojciech J. Stec,

Michael F. Summers,

Gerald Zon

Publication year - 1986

Publication title -

nucleic acids research

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 9.008

H-Index - 537

eISSN - 1362-4954

pISSN - 0305-1048

DOI - 10.1093/nar/14.22.9081

Subject(s) - diastereomer , moiety , oligonucleotide , sulfur , stereochemistry , nuclear magnetic resonance spectroscopy , phosphate , high performance liquid chromatography , proton nmr , biology , dna , chemistry , organic chemistry , biochemistry

2D-NOE and 1H NMR chemical shift data obtained for the title oligonucleotides were compared with similar data previously reported [Broido et al. (1985) Eur. J. Biochem. 150, 117-128] for the unmodified "parent" structure, [d(GGAATTCC)]2. The spectroscopically detectable structural perturbations caused by replacement of phosphate oxygen with sulfur were mostly localized within the GsA moiety, and were greater for the Rp configuration wherein sulfur is oriented into the major groove of the B-helix. UV-derived Tm measurements gave the following order of stability for the duplexes in 0.4 M NaCl: unmodified (33.9 +/- 0.1 degrees C) approximately Sp-Sp (34.1 degrees C) greater than Rp-Rp (31.7 degrees C). The title compounds were prepared by a new and convenient synthetic route which utilized HPLC to separate the diastereomeric O-ethyl phosphorothioate precursors, (Rp)- and (Sp)-d[GG(S,Et)AATTCC], for subsequent de-ethylation by ammonia in water.

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