0000000000266385
AUTHOR
Omar Boulanouar
Low energy electrons and ultra-soft X-rays irradiation of plasmid DNA. Technical innovations
Abstract In this paper we present in a first part the latest results of our group which are in relation with the study of DNA damages inflicted by low energy electrons (0-20 eV) in ultra-high vacuum as well as in air under atmospheric conditions. A short description of the drop-casting technique we developed to produce thin and nanometre-scaled DNA layers onto graphite sheets is given. We provide the absolute cross-section for loss of supercoiled topology of plasmid DNA complexed with 1,3-diaminopropane (Dap) in the vacuum under 10 eV electron impact and suggest a specific pathway for the dissociation of the transient negative ion formed by resonant capture of such a low energy electron (LE…
Complexation des acides aminés basiques arginine, histidine et lysine avec l’ADN plasmidique en solution aqueuse : participation à la capture de radicaux sous irradiation X à 1,5 keV
L’environnement chimique de l’ADN en situation biologique est complexe notam-ment en raison de la presence d’histones, proteines nucleaires, associees en quantite approximativement egales a l’ADN pour former la chromatine. Les histones possedent de nombreux radicaux basiques arginine et lysine charges positivement et dont la majorite se trouve sur les chaines emergentes, l’ADN presente quant a lui des charges negatives sur ses groupements phosphates localises tout au long de la double helice. Dans cette etude, la complexite de la structure de la chromatine nucleaire est dans un premier temps mimee en solution aqueuse par la formation de complexes entre un ADN plasmidique sonde et les trois …
Auto-assembly of nanometer thick, water soluble layers of plasmid DNA complexed with diamines and basic amino acids on graphite: Greatest DNA protection is obtained with arginine.
Abstract We have investigated the ability of diamines as well as basic amino acids to condense DNA onto highly ordered pyrolytic graphite with minimum damage after re-dissolution in water. Based on a bibliographic survey we briefly summarize DNA binding properties with diamines as compared to basic amino acids. Thus, solutions of DNA complexed with these linkers were drop-cast in order to deposit ultra-thin layers on the surface of HOPG in the absence or presence of Tris buffer. Atomic Force Microscopy analyses showed that, at a fixed ligand-DNA mixing ratio of 16, the mean thickness of the layers can be statistically predicted to lie in the range 0–50 nm with a maximum standard deviation ±…