Bioinformatics

ROS is a major endogenous DNA damage causing source and 8-oxo-dG adduct have been mostly studied. Lipid peroxidation derived aldehydes are also risk to DNA. Different adducts produced are malondialdehyde-, propano- and etheno- consequent DNA adducts. Despite of lipid peroxidation and oxygen products, cells also carries many other reactive molecule specie that can be a basis of DNA damage, such as methylating agents. 7-methyl-guanine, 7-(2-hydroxyethyl) guanine, O6-methyl-guanine, O4-methylthymine, and, 3-methyladenine, of which O6-methylguanine is the major cause of mutations, all of these are most important adducts for DNA damage. High frequency of DNA damage occurs due to endogenous factors in contrast with exogenous damages. The high rate of endogenous DNA damage is related with a competent damage repair, important for the survival of a cell. Most of the DNA damage of endogenous nature is fixed up by BER pathway, mismatch repair and O6-methylguanine DNA methyltransferase. Dissoc...

DNA damages are repaired by many overlapping repair pathways to remove damaged DNA and it also determines cell fate. Nucleotide excision repair pathways repair oxidative base damage and base excision repair pathway removes helical distortions in DNA structure, damages caused by ultra violet radiations and other exogenous oxidative damages. Along with these pathways, DNA Mismatch repair and DNA strand break repair pathways also important in repairing damaged DNA . Endogenus and Exogenus DNA damaging agents: Lipid peroxidation Phospholipid residues of fatty acids are much sensitive to oxidation. Unsaturated fatty acid yields lipid hydroperoxides upon oxidation as its initial products. They may react either with metals or reduced by glutathione peroxidases to produce aldehydes, epoxides etc and unreactive fatty acid alchohals. Malondialdehyde (MDA), croton aldehyde, 4-hydroxynonenal (HNE) and acrolein are major lipid peroxidation aldehyde reactive products which damage DNA by fo...