DNA photolyase

DNA photolyase

DNA Repair During Aging

Published in Alvaro Macieira-Coelho, Molecular Basis of Aging, 2017

One type of dimer results from covalent linkage between two neighboring pyrimidine bases and forms a cyclobutane ring. The DNA photolyase directly opens the ring in a light-dependent process.48 This photolyase was found in bacteria, plants and animals — with the highest significance probably in plants. Interestingly, this enzyme was found in internal organs which never get in contact with exogenous UV. Possibly it is used to remove damages caused by endogenous UV that is produced together with visible light inside the cells.49

Assessing the impact of low level laser therapy (LLLT) on biological systems: a review

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Journal Information

Published in International Journal of Radiation Biology, 2019

Ruwaidah A. Mussttaf, David F. L. Jenkins, Awadhesh N. Jha

It has been reported that the photo-reactivating enzyme (DNA photolyase) distinguishes one type of DNA damage as its substrate (i.e. the cyclobutane-type pyrimidine dimer), and combines with these dimers in the dark (Smith 1991). However, when exposing the enzyme-substrate complex to visible light, the enzyme uses the absorbed energy of light to split the dimer to produce repaired (original) DNA. Mbene (2008) treated wounded human skin fibroblast cells by He-Ne laser with 5 J/cm2 and 16 J/cm2 doses. Irradiation with 5 J/cm2 and 16 J/cm2 showed insignificant change in DNA damage, as determined by alkaline comet assay, at 1 h when compared to their respective controls. However, a significant decrease in DNA damage at 24 h incubation due to the mechanism of DNA repair was shown (Mbene 2008).

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DNA Repair During Aging

Assessing the impact of low level laser therapy (LLLT) on biological systems: a review