TY  - JOUR
A1  - Hahn, Marc Benjamin
A1  - Meyer, Susann
A1  - Schröter, Maria-Astrid
A1  - Seitz, Harald
A1  - Kunte, Hans-Jörg
A1  - Solomun, Tihomir
A1  - Sturm, Heinz
T1  - Direct electron irradiation of DNA in a fully aqueous environment
BT  - Damage determination in combination with Monte Carlo simulations
JF  - Physical chemistry, chemical physics : PCCP ; a journal of European chemical societies
N2  - We report on a study in which plasmid DNA in water was irradiated with 30 keV electrons generated by a scanning electron microscope and passed through a 100 nm thick Si3N4 membrane. The corresponding Monte Carlo simulations suggest that the kinetic energy spectrum of the electrons throughout the water is dominated by low energy electrons (<100 eV). The DNA radiation damage, single-strand breaks (SSBs) and double-strand breaks (DSBs), was determined by gel electrophoresis. The median lethal dose of D-1/2 = 1.7 +/- 0.3 Gy was found to be much smaller as compared to partially or fully hydrated DNA irradiated under vacuum conditions. The ratio of the DSBs to SSBs was found to be 1 : 12 as compared to 1 : 88 found for hydrated DNA. Our method enables quantitative measurements of radiation damage to biomolecules (DNA, proteins) in solutions under varying conditions (pH, salinity, co-solutes) for an electron energy range which is difficult to probe by standard methods.
Y1  - 2016
U6  - https://doi.org/10.1039/c6cp07707b
SN  - 1463-9076
SN  - 1463-9084
VL  - 19
IS  - 3
SP  - 1798
EP  - 1805
PB  - RSC Publ.
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Hahn, Marc Benjamin
A1  - Solomun, Tihomir
A1  - Wellhausen, Robert
A1  - Hermann, Sabrina
A1  - Seitz, Harald
A1  - Meyer, Susann
A1  - Kunte, Hans-Jörg
A1  - Zeman, Johannes
A1  - Uhlig, Frank
A1  - Smiatek, Jens
A1  - Sturm, Heinz
T1  - Influence of the Compatible Solute Ectoine on the Local Water Structure: Implications for the Binding of the Protein G5P to DNA
JF  - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry
N2  - Microorganisms accumulate molar concentrations of compatible solutes like ectoine to prevent proteins from denaturation. Direct structural or spectroscopic information on the mechanism and about the hydration shell around ectoine are scarce. We combined surface plasmon resonance (SPR), confocal Raman spectroscopy, molecular dynamics simulations, and density functional theory (DFT) calculations to study the local hydration shell around ectoine and its influence on the binding of a gene-S-protein (G5P) to a single-stranded DNA (dT(25)). Due to the very high hygroscopicity of ectoine, it was possible to analyze the highly stable hydration shell by confocal Raman spectroscopy. Corresponding molecular dynamics simulation results revealed a significant change of the water dielectric constant in the presence of a high molar ectoine concentration as compared to pure water. The SPR data showed that the amount of protein bound to DNA decreases in the presence of ectoine, and hence, the protein-DNA dissociation constant increases in a concentration-dependent manner. Concomitantly, the Raman spectra in terms of the amide I region revealed large changes in the protein secondary structure. Our results indicate that ectoine strongly affects the molecular recognition between the protein and the oligonudeotide, which has important consequences for osmotic regulation mechanisms.
Y1  - 2015
U6  - https://doi.org/10.1021/acs.jpcb.5b09506
SN  - 1520-6106
VL  - 119
IS  - 49
SP  - 15212
EP  - 15220
PB  - American Chemical Society
CY  - Washington
ER  -