紫外線によるDNA損傷の光回復

概要

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Photoreactivation-a reduction in the effect of ultraviolet irradiation by subsequent exposure to longer wavelengths-stems from at least two different kinds of process. The first is direct, non-enzymatic short-wavelength reactivation and photoenzymemediated repair of ultraviolet radiation damage to DNA, while the second (indirect photoreactivation) is an enhancement of light-independent repairs due to physiological changes induced in cells by light.<BR>Enzymatic photoreactivation is an enzymatic process in which damage induced by ultraviolet radiation is repaired with light of longer wavelengths (300-500nm). It is achieved by a photoreactivating enzyme. On the molecular level, photoreactivating enzyme splits pyrimidine dimers in DNA into the constituent pyrimidines. Thus, photoreactivating enzyme has biological importance because of its role in one mode of DNA repair and is also of physico-chemical interest as an enzyme which utilizes light for its catalytic action.<BR>Purfied <I>Escherichia coli</I> photoreactivating enzyme is a single polypeptide of Mr 49.000 which has absorption peaks at 280 and 380nm and, upon denaturation, releases a chromophore that has the properties of flavin adenine dinucleotide, indicating that flavin is an intrinsic chromophore of the enzyme.
日本生物物理学会の論文