5-hydroxyuracil

5-Hydroxyuracil is a hydroxylated derivative of the nucleobase uracil. It is a minor product of DNA damage and can be formed in DNA by the action of ionizing radiation or by reaction with hydroxyl radicals produced by various cellular processes.

Structure and Properties

5-Hydroxyuracil, also known as 5-OHU, is a pyrimidine derivative. It has a molecular formula of C₄H₄N₂O₃ and a molecular weight of 128.09 g/mol. The structure of 5-hydroxyuracil consists of a pyrimidine ring, which is a six-membered ring with two nitrogen atoms and four carbon atoms, with a hydroxyl group attached at the 5-position.

Formation and Repair

5-Hydroxyuracil can be formed in DNA by the action of ionizing radiation or by reaction with hydroxyl radicals produced by various cellular processes. It is one of the many types of damage that can occur to DNA.

The repair of 5-hydroxyuracil in DNA is carried out by the base excision repair pathway. This involves the removal of the damaged base by a DNA glycosylase enzyme, followed by the filling in of the resulting gap by a DNA polymerase and the sealing of the nick by a DNA ligase.

Biological Significance

The presence of 5-hydroxyuracil in DNA can lead to mutations, as it can mispair with adenine during DNA replication. This can result in a G:C to A:T transition mutation. Therefore, the efficient repair of 5-hydroxyuracil is important for maintaining the integrity of the genetic information.

See Also

• Uracil
• DNA repair
• Base excision repair
• Mutation