TY  - JOUR
A1  - Ribar, Anita
A1  - Huber, Stefan E.
A1  - Smialek, Malgorzata A.
A1  - Tanzer, Katrin
A1  - Neustetter, Michael
A1  - Schürmann, Robin
A1  - Bald, Ilko
A1  - Denifl, Stephan
T1  - Hydroperoxyl radical and formic acid formation from common DNA stabilizers upon low energy electron attachment
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - 2-Amino-2-(hydroxymethyl)-1,3-propanediol (TRIS) and ethylenediaminetetraacetic acid ( EDTA) are key components of biological buffers and are frequently used as DNA stabilizers in irradiation studies. Such surface or liquid phase studies are done with the aim to understand the fundamental mechanisms of DNA radiation damage and to improve cancer radiotherapy. When ionizing radiation is used, abundant secondary electrons are formed during the irradiation process, which are able to attach to the molecular compounds present on the surface. In the present study we experimentally investigate low energy electron attachment to TRIS and methyliminodiacetic acid ( MIDA), an analogue of EDTA, supported by quantum chemical calculations. The most prominent dissociation channel for TRIS is through hydroperoxyl radical formation, whereas the dissociation of MIDA results in the formation of formic and acetic acid. These compounds are well-known to cause DNA modifications, like strand breaks. The present results indicate that buffer compounds may not have an exclusive protecting effect on DNA as suggested previously.
Y1  - 2018
U6  - https://doi.org/10.1039/c7cp07697e
SN  - 1463-9076
SN  - 1463-9084
VL  - 20
IS  - 8
SP  - 5578
EP  - 5585
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Schürmann, Robin Mathis
A1  - Tsering, Thupten
A1  - Tanzer, Katrin
A1  - Denifl, Stephan
A1  - Kumar, S. V. K.
A1  - Bald, Ilko
T1  - Resonant Formation of Strand Breaks in Sensitized Oligonucleotides Induced by Low-Energy Electrons (0.5-9 eV)
JF  - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition
N2  - Halogenated nucleobases are used as radiosensitizers in cancer radiation therapy, enhancing the reactivity of DNA to secondary low-energy electrons (LEEs). LEEs induce DNA strand breaks at specific energies (resonances) by dissociative electron attachment (DEA). Although halogenated nucleobases show intense DEA resonances at various electron energies in the gas phase, it is inherently difficult to investigate the influence of halogenated nucleobases on the actual DNA strand breakage over the broad range of electron energies at which DEA can take place (<12 eV). By using DNA origami nanostructures, we determined the energy dependence of the strand break cross-section for oligonucleotides modified with 8-bromoadenine ((8Br)A). These results were evaluated against DEA measurements with isolated (8Br)A in the gas phase. Contrary to expectations, the major contribution to strand breaks is from resonances at around 7 eV while resonances at very low energy (<2 eV) have little influence on strand breaks.
KW  - cancer radiation therapy
KW  - dissociative electron attachment
KW  - DNA origami
KW  - DNA radiation damage
KW  - radiosensitizers
Y1  - 2017
U6  - https://doi.org/10.1002/anie.201705504
SN  - 1433-7851
SN  - 1521-3773
VL  - 56
SP  - 10952
EP  - 10955
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Schuermann, Robin
A1  - Tanzer, Katrin
A1  - Dabkowska, Iwona
A1  - Denifl, Stephan
A1  - Bald, Ilko
T1  - Stability of the Parent Anion of the Potential Radiosensitizer 8-Bromoadenine Formed by Low-Energy (< 3 eV) Electron Attachment
JF  - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry
N2  - 8-Bromoadenine ((8Br)A) is a potential DNA radiosensitizer for cancer radiation therapy due to its efficient interaction with low-energy electrons (LEEs). LEEs are a short-living species generated during the radiation damage of DNA by high-energy radiation as it is applied in cancer radiation therapy. Electron attachment to (8Br)A in the gas phase results in a stable parent anion below 3 eV electron energy in addition to fragmentation products formed by resonant exocyclic bond cleavages. Density functional theory (DFT) calculations of the (8Br)A(-) anion reveal an exotic bond between the bromine and the C8 atom with a bond length of 2.6 angstrom, where the majority of the charge is located on bromine and the spin is mainly located on the C8 atom. The detailed understanding of such long-lived anionic states of nucleobase analogues supports the rational development of new therapeutic agents, in which the enhancement of dissociative electron transfer to the DNA backbone is critical to induce DNA strand breaks in cancerous tissue.
Y1  - 2017
U6  - https://doi.org/10.1021/acs.jpcb.7b02130
SN  - 1520-6106
VL  - 121
SP  - 5730
EP  - 5734
PB  - American Chemical Society
CY  - Washington
ER  -