Phosphonoacetate (PACE) modified oligonucleotides show great potential as biological modifiers in a wide variety of research applications. PACE monomers are part of a family of Phosphonocarboxylate monomers. The monomers can be easily incorporated into complex oligonucleotides and are compatible with a wide variety of other sugar or heterobase modifications. PACE DNA can be conjugated through the carboxylic acid functional group. They have been shown to be active in siRNA duplexes and accelerate the initial rate of cleavage by RNase H-1 when incorporated with phosphorothioates. However, the most interesting observation to date is that they exhibit an unprecedented enhancement in penetration of cultured cells.
PACE monomers are fully soluble in acetonitrile at a recommended concentration of 0.1M and are compatible with standard DNA synthesizers. As an optimal cycle, we recommend using DCI as an activator (30-3150-XX) and a 15 minute coupling time. Following coupling, cap using Unicap (10-4410-XX) with a regular coupling time and then oxidize using 0.5 M CSO for 3 minutes. Alternatively, a 33 minute coupling time using 0.45 M tetrazole, oxidation using low-water iodine (40-4032-XX) followed by capping with 6.5% DMAP as Cap B will give acceptable results. For deprotection, pre-treat the synthesis column with 1.5% DBU in anhydrous acetonitrile for 60 minutes at room temperature to remove 1,1-dimethyl-2-cyanoethyl protecting groups. Rinse the column with acetonitrile, dry under argon and complete the deprotection with 40% aqueous methylamine for 2 hours at room temperature.