Wenjian Ma En-Hua Cao*

(Institute of Biophysics, Academia Sinica, Beijing 100101,P.R.China)

*Correspondence should be addressed to:

En-Hua Cao

Institute of Biophysics

Academia Sinica

15 Datun Road, Chaoyang District

Beijing 100101, P.R.China

Fax: +86-10-62027837

E-mail: caoeh@sun5.ibp.ac.cn

 

Key Words: DNA damage; phenthroline-Cu²⁺ complex ; oxidative stress; reactive oxygen species; chemiluminescence.

The chemiluminescence(CL) concomitant with Phen-Cu²⁺/ascorbate/H₂O₂-induced DNA damage was studied. The emission intensity increases linearly with increasing DNA concentration. An emission spectrum with maximal wavelength at about 410 nm was obtained. The luminescence was inhibited by histone in a histone concentration dependent manner. The CL is characteristic of guanine. Of five common bases only guanine can give rise to luminescence. Investigation of various guanine derivatives show that emission intensity weakens when N⁷ and O⁶ guanine methyl derivatives replace guanine, whereas it is enhanced when the N⁹ site is linked with ribose or ribose phosphate and further enhanced with increasing of phosphate number. Compared with guanine riboside or guanine nucleotide, guanine deoxyriboside or guanine nucleotide was more powerful in producing CL. The luminescence was inhibited by all three classes of reactive oxygen species’ (•OH, , ¹O₂) scavengers with ¹O₂ scavenger being the most powerful. By comparing the effect of scavengers on the luminescence of DNA with dGMP, we propose that •OH may not be the principle species responsible for DNA damage of above system.