The genome of all living organisms are constantly exposed to exogenous and endogenous DNA-damaging agents and the greatest amount of damage is inflicted by the endogenous agents water and oxygen, which modify primarily the aromatic DNA bases. While ROS (Reactive Oxygen Species) such as hydroxyl radicals convert guanine (G) to 8-oxoguanine and thymine (T) to thymine glycol, water brings about the deamination of all bases carrying exocyclic amino groups (Ref.1).
Among the most deleterious of ROS-induced adducts is oxoG (7,8-dihydro-8-oxoguanine), which is formed by the oxidation of the guanine base in DNA. Guanine bases have a strong preference to pair with cytosine (C), but oxoG can pair both in Watson–Crick mode with cytosine and in Hoogsteen mode with adenine (A). [...]