Figure 2.

PAGE analysis of fully deprotected and RP-HPLC-purified oligonucleoside phosphorothioates under denaturing conditions (20% polyacrylamide–7 M urea, 1× TBE buffer, pH 8.3). Left lane: CpG ODN 1555 synthesized from commercial 2-cyanoethyl deoxyribonucleoside phosphoramidites and deprotected by treatment with pressurized ammonia gas (∼10 bar) for 12 h at 25°C. Middle lane: CpG ODN fma1555 synthesized from phosphoramidites 1a–d and deprotected by treatment with pressurized ammonia gas (∼10 bar) for 12 h at 25°C followed by heating in 1× PBS (pH 7.2) for 626 h at 37°C. Right lane: ODN fma1556 synthesized and deprotected under conditions identical to those used for CpG ODN fma1555. Oligonucleotides are visualized as purple bands upon staining the gel with Stains-all. Bromophenol blue is used as a marker and shows as a large band, in each lane, at the bottom of the gel.