MOLECULAR BIOLOGY: ON DNA-REPAIR ENZYMES:
The agents that cause oxidative damage to DNA include oxygen radicals and ionizing radiation. Oxidation of a guanosine base to form oxoG produces a subtle structural transformation that results in deleterious mutations because DNA polymerases misread oxoG as a thymine (T) during genome replication prior to cell division. The human oxoG repair enzyme (hOGG1) catalyses the excision of oxoG in the first step of base excision repair.
Structural studies of the glycosylase enzymes involved in the repair process reveal common features of damaged-base recognition. These include enzyme-initiated DNA distortion that flips the damaged base out from the DNA double helix for recognition within a base-specific cavity of the enzyme. (OGG1)
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