TY - GEN A1 - Schröter, Maria-Astrid T1 - Structural changes in plasmid DNA caused by radiation and its protection by Ectoine: an AFM analysis N2 - Most ionizing radiation in water ends in an avalanche of low energy electrons which play a dominant role together with OH-radicals in damaging DNA. In the present study we irradiated plasmid DNA with electrons (primary energy 30keV) under physiological conditions, performed with as well as without Ectoine. Ectoine is a compatible solute, synthesized and accumulated in molar concentration within bacteria to withstand osmotic stress or different other stressors. Plasmid DNA (pUC19, 2686 bp) was studied due to its supercoiled isoform which is highly sensitive to radiation damage. In biochemistry gel electrophoresis is applied for structural analysis of DNA. Although it is a standard technique, a reliable discrimination of short fragments caused by radiation is often difficult. AFM is also commonly used for imaging susceptible biomolecules and, since it is based on a single molecule observation, for analysis of contour lengths of linear DNA as well. Therefore, in our study the structural changes in plasmid DNA after irradiation with different doses were quantitatively analyzed by means of intermittent contact AFM. The figure shows representative AFM images of electron irradiated pUC19 DNA (bar=200nm). For AFM imaging the DNA was chemically fixed on ultra-smooth mica. As can be clearly seen, with increasing radiation dose the number of undamaged DNA declines and fragmented DNA arises (A, B). In aqueous Ectoine solution (1M) the effect of radiation on DNA is dramatically depressed. Ectoine apparently confers protection even against high radiation: the plasmids remain predominantly in the supercoiled isoform (D). Therefore, we strongly believe that Ectoine is a potent protective substance of DNA against ionizing radiation. T2 - AFM BioMed CY - Krakau, Poland DA - 04.09.2017 KW - AFM KW - Plasmid DNA KW - Ectoine KW - Electron radiation PY - 2017 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/42027 AN - OPUS4-42027 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany