Specific modified DNA bases are usually used to study DNA damages and repair solution.
The 7-deaza purine monomers lack groups critical for hydrogen bonding.
The 8-oxo purine monomers allow investigation of the Oligo structure and activity. 8-oxo mutation occurs naturally when DNA is subjected to oxidative conditions or ionizing radiation.
5,6-Dihydro pyrimidines are naturally occurring compounds that are structural components of alanine transfer RNA.
Methylating agents are common carcinogens which function by methylation of exocyclic Amine sites in DNA. The resultant mutagenic effects can be mimicked using oligonucleotides containing methylated nucleosides like O6-Me-dG.