Zwang Theodore J, Tse Edmund C M, Zhong Dongping, Barton Jacqueline K
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Departments of Chemistry and Physics, The Ohio State University, Columbus, Ohio 43210, United States.
ACS Cent Sci. 2018 Mar 28;4(3):405-412. doi: 10.1021/acscentsci.8b00008. Epub 2018 Mar 7.
How birds sense the variations in Earth's magnetic field for navigation is poorly understood, although cryptochromes, proteins homologous to photolyases, have been proposed to participate in this magnetic sensing. Here, in electrochemical studies with an applied magnetic field, we monitor the repair of cyclobutane pyrimidine dimer lesions in duplex DNA by photolyase, mutants of photolyase, and a modified cryptochrome. We find that the yield of dimer repair is dependent on the strength and angle of the applied magnetic field even when using magnetic fields weaker than 1 gauss. This high sensitivity to weak magnetic fields depends upon a fast radical pair reaction on the thymines leading to repair. These data illustrate chemically how cyclobutane pyrimidine dimer repair may be used in a biological compass informed by variations in Earth's magnetic field.
鸟类如何感知地球磁场变化以进行导航，目前尚不清楚，尽管有人提出，与光解酶同源的蛋白质隐花色素参与了这种磁感测。在这里，在施加磁场的电化学研究中，我们监测了光解酶、光解酶突变体和一种修饰的隐花色素对双链DNA中环丁烷嘧啶二聚体损伤的修复情况。我们发现，即使使用低于1高斯的磁场，二聚体修复的产率也取决于所施加磁场的强度和角度。这种对弱磁场的高灵敏度取决于胸腺嘧啶上快速的自由基对反应，从而导致修复。这些数据从化学角度说明了环丁烷嘧啶二聚体修复如何用于由地球磁场变化告知的生物指南针中。
