Template-directed synthesis on the pentanucleotide CpCpGpCpC.

The pentanucleotide CpCpGpCpC facilitates the synthesis of oligomers containing G and C from a mixture of the two activated mononucleotides (guanosine 5'-phosphor)-2-methylimidazolide and (cytidine 5'-phosphor)-2-methylimidazolide. The major pentameric product of the template-directed reaction is all 3' to 5'-linked and has the sequence pGpGpCpGpG, which is complementary to that of the template. It can be obtained in a yield of up to 17%, based on the input of the template. The 3' to 5' isomer of GpG is elongated on the template to give GpGpC, GpGpCpG and GpGpCpGpG, while the 2' to 5' isomer does not initiate the synthesis of detectable amounts of longer oligomers.