PHOTOCHEMICAL PROPERTIES OF ESCHERICHIA-COLI DNA PHOTOLYASE - A FLASH-PHOTOLYSIS STUDY
PHOTOCHEMICAL PROPERTIES OF ESCHERICHIA-COLI DNA PHOTOLYASE - A FLASH-PHOTOLYSIS STUDY
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DOI：
10.1021/bi00373a006
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发表时间：
1986-12-16
期刊：
影响因子：
2.9
通讯作者：
SANCAR, A
中科院分区：
文献类型：
--
作者：
HEELIS, PF;SANCAR, A
大肠杆菌DNA光裂合酶含有一个稳定的中性蓝自由基，参与DNA中嘧啶二聚体的光敏修复。我们已经研究了照明的影响，对自由基使用的光。> 520 nm的相机闪光灯或激光。我们发现，这两种类型的照射导致黄素自由基的光还原，量子产率为0.10 ±-。0.02.虽然照相机闪光灯的光还原在没有电子供体（二硫苏糖醇）的情况下是最小的，但在532 nm处的激光闪光光解在存在或不存在电子供体的情况下将黄素减少到相同的程度。因此，可以得出结论，光还原的主要步骤涉及电子供体，这是酶本身的组成部分。激光闪光光解在420 nm处产生瞬态吸收带，这可能代表最低激发双重态的吸收。图形 **。并以一级动力学衰减，k1 = 0.8 ×106秒-1光还原数据结合最近的研究结果的连二亚硫酸盐还原酶的活性表明，电子捐赠的激发态的E. sbd。FADH是E. coliDNA光解酶。
Escherichia coli DNA photolyase contains a stable neutral blue radical that is involved in photosensitized repair of pyrimidine dimers in DNA. We have investigated the effect of illumination on the radical using light of .lambda. > 520 nm from either a camera flash or laser. We find that both types of irradiations result in the photoreduction of the flavin radical with a quantum yield of 0.10 .+-. 0.02. While photoreduction with the camera flash is minimal in the absence of an electron donor (dithiotheritol), laser flash photolysis at 532 nm reduces the flavin to the same extent in the presence or absence or an electron donor. Thus, it is concluded that the primary step on photoreduction involves an electron donor that is a constituent of the enzyme itself. Laser flash photolysis produces a transient absorption band at 420 nm that probably represents the absorption of the lowest excited doublet state .**GRAPHIC**. of the radical and decays with first-order kinetics with k1 = 0.8 .times. 106 s-1. The photoreduction data combined with the results of recent studies on the activity of dithionite-reduced enzyme suggest that electron donation by excited states of E .sbd. FADH is the mechanism of flavin photosensitized dimer repair by E. coli DNA photolyase.