✍ Scribed by Frank Seela; Yaoming Chen
No coin nor oath required. For personal study only.
The 7‐deaza‐2′‐deoxy‐7‐methylguanosine (2b) [9], which is the glycosylic‐bond‐stable, noncharged analogue of 2′‐deoxy‐7‐methylguanosine (1b), was incorporated in DNA by solid‐phase synthesis. As building blocks, the protected phosphonatc 3a and the phosphoramidite 3b were prepared. The 7‐methyl group of 2b stabilizes the B‐DNA duplex compared to 7‐deaza‐2′‐deoxyguanosine but does not induce a B‐Z transition as it is known from compound 1b. The stabilization by the 7‐deaza‐7‐methylguanine moiety is sequence‐dependent, and the nearest‐neighbor influence is different from that of 7‐deazaguanine. Homooligonucleotides of 2b show sigmoidal melting indicating a highly ordered single‐stranded structure. In general, Oligonucleotides containing 2b are very stable against hydrolysis with calf‐spleen phosphodiesterase (CS‐PDE, 5′ → 3′ exonuclease), while phosphodiester hydrolysis with snake‐venom phosphodiesterase (SV‐PDE, 3′ → 5′ exonuclease) is only slightly reduced.
📜 SIMILAR VOLUMES
Oligodeoxyribonucleotides containing 7-deaza-2'-deoxy-8-methylguanosine (mRc7G,; 2b) were prepared. For this purpose, the phosphonate 3a and the phosphoramidite 3b were synthesized and employed in solidphase oligodeoxyribonucleotide synthesis. The structures and the thermodynamic data of duplex form
Oligonucleotides containing 7-substituted 8-aza-7-deazaguanines ( 6-amino-1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-ones) were prepared by automated solid-phase synthesis. A series of 7-alkynylated 8aza-7-deaza-2'-deoxyguanosines (see 4a ± d) were synthesized with the 7-iodonucleoside 3c as starting