Nucleic Acids Research, Vol 26, Issue 11 2650-2658, Copyright © 1998 by Oxford University Press
B Nawrot, M Boczkowska, M Wojcik, M Sochacki, S Kazmierski and WJ Stec
Diastereomeric dithymidine methanephosphonamidates (TnpmT) were synthesized
by reaction of 3'-amino-3'-deoxythymidine with 3'- O -
acetylthymidin-5-yl-methanephosphonochloridate. Separated dinucleotide
TnpmT(fast) and TnpmT(slow) diastereomers were used as building blocks to
prepare chimeric dodecathy-midylates, possessing one to four modified
linkages, by means of phosphoramidite automated solid phase synthesis. As
expected, the methanephosphonamidate internucleotide linkage is resistant
to nuclease P1, snake venom PDE and 3'-exonuclease from human plasma.
Degradation of dodecathymidylates possessing modified internucleotide
linkages in alternate positions proved the 'hopping' properties of
3'-exonuclease. Oligo(deoxyribonucleotide methanephosphonamidates) were
tested for their binding affinity to complementary oligomers in thermal
denaturation experiments. All the oligomers showed lower binding affinity
to DNA and RNA targets, however, oligomers originating from the TnpmT(fast)
dimeric unit exhibited better hybridization properties than their
diastereomeric TnpmT(slow) counterparts. A lowering of T m of approximately
2.4 degrees C (1.0-1.8 degrees C) was observed for each introduced
TnpmT(fast) modification and 6.0 degrees C (4.2-5.0 degrees C) for each
TnpmT(slow) modification in duplexes of modified dodecathymidylates with
dA12(A12) oligomers. The oligo(deoxyribonucleoside methanephosphonamidate)
designated F4, possessing four modified methanephosphonate linkages
originating from the TnpmT(fast) diastereomeric unit, exhibits a tendency
for triplex formation, as was demonstrated in thermal denaturation
experiments with the d(A21C4T21) hairpin oligomer.
ARTICLES
Novel internucleotide 3'-NH-P(CH3)(O)-O-5' linkage. Oligo(deoxyribonucleoside methanephosphonamidates); synthesis, structure and hybridization properties
Department of Bioorganic Chemistry, Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Lodz, Poland. bnawrot@lodz.pdi.net
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