Photolyase

Photolyases are enzymes which are involved in the repair of DNA. You will manage the resolution of cyclobutane pyrimidine dimers (CPD ) and (6-4) photoproducts, which are formed by ultraviolet radiation upon exposure of DNA.

Occurrence

Photolyases have been found in prokaryotes, eukaryotes and archaea. In higher mammals, including humans, lack functional variants of these proteins, whereas they could be detected in marsupials, such as the house - shrew opossum ( Monodelphis domestica) or the rabbit kangaroo Potorous didactylus.

Structure

The photolyase from Escherichia coli has a molecular mass of 54 kDa. The primary cofactor in all photolyases is the redox-active flavin adenine dinucleotide. They also have an antenna complex from either the pterin cofactor MTHF ( methylenetetrahydrofolate ) or the deazaflavin cofactor 8- HDF (8- hydroxy-5- Desazariboflavin ) is.

Function

Photolyases bind in the active site depending on photolyase class either CPDs or (6-4) photoproducts in DNA. By blue or ultraviolet exposure of the antenna complex is excited and transfers this excitation to the present reduced redox cofactor ( FADH - ). From this, an electron jumps to the DNA damage in the active site, which dissolves thereby. Flavin is then restored by an electron transfer from tryptophan to the enzyme surface to its reduced state. In contrast to other repair mechanisms, the correction takes place without cutting the DNA.