Stereo-enriched phosphorothioate oligodeoxynucleotides: synthesis, biophysical and biological properties.
Stereo-enriched [Rp] and [Sp]-phosphorothioate oligodeoxynucleotides are synthesized using oxazaphospholidine derivatized monomers. Three different designs of phosphorothioate oligodeoxynucleotides (PS-oligos), (i) stereo-enriched all-[Rp] or all-[Sp] PS-linkages, (ii) stereo-random mixture of PS-linkages, and (iii) segments containing certain number of stereo-enriched [Rp] and [Sp] PS-linkages ([Sp-Rp-Sp] or [Rp-Sp-Rp]), have been studied. Thermal melting studies of these PS-oligos with RNA complementary strands showed that the binding affinities are in the order [Rp] > [Sp-Rp-Sp]-[Rp-Sp-Rp] > stereo-random > [Sp]. Circular dichroism (CD) studies suggest that the stereochemistry of the PS-oligo does not affect the global conformation of the duplex. The in vitro nuclease stability of these PS-oligos is in the order [Sp] > [Sp-Rp-Sp] > stereo-random > [Rp]. The RNase H activation is in the order [Rp] > stereo-random > [Rp-Sp-Rp] > [Sp] > [Sp-Rp-Sp]. Studies in a cancer cell line of PS-oligos targeted to MDM2 mRNA showed that all oligos had similar biological activity under the experimental conditions employed. Protein- and enzyme-binding studies showed insignificant stereo-dependent binding to proteins. The [Sp] and [Sp-Rp-Sp] chimeric and stereo-random PS-oligos that contained a CpG motif showed higher cell proliferation than [Rp] PS-oligo of the same sequence.
Yu
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Hybridon, Inc., Milford, MA 01757, USA.
Kandimalla
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ER
Roskey
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A
Zhao
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Q
Chen
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Chen
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J
Agrawal
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S
D000818:Animals; D001483:Base Sequence; D002455:Cell Division / Q000187:drug effects; D002942:Circular Dichroism; D008297:Male; D051379:Mice; D009687:Nuclear Proteins; D009943:Organophosphorus Compounds / Q000737:chemistry*; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors; D051736:Proto-Oncogene Proteins c-mdm2; D013056:Spectrophotometry, Ultraviolet; D013873:Thionucleotides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
D009687:Nuclear Proteins; D009943:Organophosphorus Compounds; D011518:Proto-Oncogene Proteins; D013873:Thionucleotides; C497207:Mdm2 protein, mouse; D051736:Proto-Oncogene Proteins c-mdm2