Complex Sequence Dependence by Excess‐Electron Transfer through DNA with Different Strength Electron Acceptors

Abstract

An independent jump: Excess electrons move through DNA by using a hopping‐type mechanism in which the pyrimidine bases dT and dC act as ‘stepping stones’. It was shown that GC base pairs, in contrast to AT base pairs, lower the efficiency of the excess‐electron transfer through the duplex. Through the use of the shown DNA hairpins, three different electron acceptors ( ) were investigated with the electron donor, reduced flavin ( ).

Investigation of Excess‐Electron Transfer in DNA Double‐Duplex Systems Allows Estimation of Absolute Excess‐Electron Transfer and CPD Cleavage Rates

“…In contrast, with BrdG (see Scheme 2), the sequence dependence was hardly resolved, which showed that electron trapping and debromination must be nearly as fast as electron transfer in this case. [20] In pure AT sequences, we observed that the acceptors BrdA and BrdG were debrominated slower than BrdU (see Scheme 2), which indicated that, in these experiments, debromination is rate determining rather than excess-electron transfer. This would allow electrons to hop over the acceptor without causing debromination.…”

“…[11] Even though the principle mechanism of excess-electron transfer, and in particular the distance dependence, [12][13][14][15][16][17][18] has been clarified, conflicting data still exist, for example, for the sequence dependence of the transfer reaction. [19][20][21][22][23][24][25][26][27] In addition, the question of whether excess-electron transfer depends on the transfer direction in the DNA duplex has not been satisfactorily investigated. Finally, we are just beginning to understand absolute hopping rates.…”

“…Keywords: cleavage · DNA repair · electron transfer · flavins · nucleobases [ fundamentally determines the outcome of the excess-electron transfer experiment. [20] When the electron acceptor BrdU (see Scheme 2) was used, we determined a sequence-dependent electron transfer with slower excess-electron movement through GC sequences. In contrast, with BrdG (see Scheme 2), the sequence dependence was hardly resolved, which showed that electron trapping and debromination must be nearly as fast as electron transfer in this case.…”

Electrochemical switching of the flavoprotein dodecin at gold surfaces modified by flavin-DNA hybrid linkers

“…͑ii͒ The DNA sequence can differ in length and composition, which may also affect the ET and adsorption properties. 31,38,[44][45][46][47] ͑iii͒ The nature of the redox center, its redox potential, and its mode of attachment vary. For instance, one or two electrons can be transferred, and additional protonation steps can be involved in ET.…”

“…[25][26][27][28] On the other hand, there are impressive reports about photoinduced electron transfer ͑ET͒ through DNA over short distances. [29][30][31] Furthermore, different groups have independently shown that ET through monolayers of short double stranded DNA ͑ds-DNA͒ adsorbed on gold is possible. [14][15][16][17][18][19][20][21][22] Here, a first approach using ds-DNA of 20 base pairs as potential molecular wire system is presented.…”