636581-04-9Relevant academic research and scientific papers
Excess Electron Transfer in DNA Studied by Pulse Radiolysis and ?3-Radiolysis of Naphthalimide and Iodouridine Modified ODN
Kawai, Kiyohiko,Kimura, Takumi,Kawabata, Kazuhiro,Tojo, Sachiko,Majima, Tetsuro
, p. 12838 - 12841 (2003)
An excess electron was attached to naphthalimide (NI) modified 12-mer oligodeoxynucleotides (ODNs) and the electron transfer in DNA was investigated by monitoring the transient absorption of NI radical anion (NIì? -) during the pulse radiolysis. Formation of the transient absorption of NIì?- was observed according to the reaction of eaq- with NI-modified ODN. Only 25% of eaq - reacting with NI-modified ODN were observed by the transient absorption of NIì?-, which corresponds to electron transfer over no more than three base pairs, suggesting a low mobility of an electron attached to DNA. Electron transfer in DNA was also studied by ?3-radiolysis of ODN containing 5-iododeoxyuridine (IU) as a second electron acceptor. Electron transfer in DNA was estimated by the protection of dehalogenation of IU offered by NI during the ?3-radiolysis of NI-and IU-modified ODNs where the spacing between the NI and IU was varied. The protection effect became very low by the insertion of three or four A-T base pairs between NI and IU. The results driven from both pulse radiolysis and ?3-radiolysis experiments were consistent with the low mobility of an excess electron in DNA, which is in strong contrast to the occurrence of the long-range hole transfer in DNA.
