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Pyrimidine dimer is a type of DNA lesion caused by UV light, involving thymine or cytosine bases. Learn about the types, mutagenesis, and repair mechanisms of pyrimidine dimers, and their role in skin cancer and XP.
Thymine dimer is a photolesion produced by UV radiation in sunlight and is considered as a potential factor causing skin cancer. Learn about its structure, repair, and simulation with molecular dynamics and quantum chemistry methods.
Thymine dimers are covalent bonds between two thymine bases in DNA caused by ultraviolet light. Learn how they affect DNA replication, mutation and repair, and see the structures of enzymes involved.
2024-10-26. Description. Dimers found in DNA chains damaged by ULTRAVIOLET RAYS. They consist of two adjacent PYRIMIDINE NUCLEOTIDES, usually THYMINE nucleotides, in which the pyrimidine residues are covalently joined by a cyclobutane ring. These dimers block DNA REPLICATION.
Direct repair of thymine dimers. UV-induced thymine dimers can be repaired by photoreactivation, in which energy from visible light is used to split the bonds forming the cyclobutane ring. Another form of direct repair deals with damage resulting from the reaction between alkylating agents and DNA.
The thymine dimer. This type of damage is introduced into DNA in cells that are exposed to ultraviolet irradiation (as in sunlight). A similar dimer will form between any two neighboring pyrimidine bases (C or T residues) in DNA.
At least five major DNA repair pathways—base excision repair (BER), nucleotide excision repair (NER), mismatch repair (MMR), homologous recombination (HR) and non-homologous end joining (NHEJ)—are active throughout different stages of the cell cycle, allowing the cells to repair the DNA damage.
