NMR Studies of Backbone-Alkylated DNA: Duplex Stability,Absolute Stereochemistry,and Chemical Shift Anomalies of Prototypal Isopropyl Phosphotriester Modified Octanucleotides, (Rp,Rp)- and (Sp,Sp)-{d-[GGA(iPr)ATTCC]}2 and - {d- [GGAA(iPr)TTCC]}2 |
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| Authors: | Donald P. Lawrence Chen Wenqiao Gerald Zon Wojciech J. Stec Bogdan Uznanski Michelle S. Broido |
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| Affiliation: | 1. Department of Chemistry , Hunter College and the Graduate School of CUNY , 695 Park Ave., New York , NY , 10021;2. Molecular Pharmacology Laboratory Division of Biochemistry and Biophysics , Food and Drug Administration , 8800 Rockville Pike, Bethesda , MD , 20892;3. Polish Academy of Sciences, Centre of Molecular and Macromolecular Studies , 90-362 , Lodz , Poland |
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| Abstract: | Abstract The DNA octamer {d-[GGAATTCC]}2 and four alkylated analogues, (Rp)-{d-[GGA(iPr)ATTCC]}2, (Sp)-{d-[GGA(iPr)ATTCC]}2, (Rp)-{d-[GGAA(iPr)TTCC]}2, and (Sp)-{d-[GGAA(iPr)TTCC]}2 have been examined using 1H and 31P NMR spectroscopies. Duplex stability, as monitored by both NMR and optical measurements, is shown to be a function of both site and stereochemistry of the phosphotriester moiety. Chemical shift changes relative to the native octamer indicate that there are long-range perturbations in the isopropylated molecules. 1H NMR is shown to be a general means by which stereochemistry at phosphorus can be determined. |
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