DNA damage from UV light

The purine and pyrimidine bases of nucleic acids absorb UV radiation strongly. UV light can be classified into three groups based on the wavelength: UV-A (315-400nm), UV-B (280-315nm) and UV-C (280 nm). UV light with longer wavelengths (UV-A and UV-B) affects DNA significantly.

The two main DNA lesions induced by UV-A and UV-B radiation are cyclobutane–pyrimidine dimers (CPDs) and 6–4 photoproducts (6–4PPs). These result in structural distortions which eventually lead to replication arrests and double-strand breaks.

Two chemical reactions of dimerization. Two DNA bases as substrates are dimerised by UV light in the reaction of photolyase.

Figure 1: UV induce nucleotide dimer.

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