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Epr, Endor And Dft Studies On X-Irradiated Single Crystals Of L-Lysine Monohydrochloride Monohydrate And L-Arginine Monohydrocloride Monohydrate, Yiying Zhou
Physics and Astronomy Dissertations
When proteins and DNA interact, arginine and lysine are the two amino acids most often in close contact with the DNA. In order to understand the radiation damage to DNA in vivo, which is always associated with protein, it is important to learn the radiation chemistry of arginine and lysine independently, and when complexed to DNA. This work studied X-irradiated single crystals of L-lysine monohydrochloride dihydrate (L-lysine·HCl·2H2O) and L-arginine monohydrochloride monohydrate (L-arginine·HCl·H2O) with EPR, ENDOR, EIE techniques and DFT calculations. In both crystal types irradiated at 66K, the carboxyl anion radical and the decarboxylation radical were detected. DFT calculations supported …
Quantum Chemical Investigations Of Nucleophilic Aromatic Substitution Reactions And Acid Dissociations Of Aliphatic Carboxylic Acids, David Henry Schory
Quantum Chemical Investigations Of Nucleophilic Aromatic Substitution Reactions And Acid Dissociations Of Aliphatic Carboxylic Acids, David Henry Schory
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Quantum chemical analysis was used to examine nucleophilic aromatic substitution reactions of fluorinated benzophenones, diphenyl sulfones, and triphenylphosphine oxides. Some experimental results for these compounds were contrary to conventional wisdom, which holds that calculated atomic charges for the aromatic sites and 13C-NMR and 19F-NMR chemical shifts should allow prediction of the preferred sites for aromatic substitution. Density functional theory (B3LYP/6-31+G*//RM1) and semi-empirical (RM1) quantum chemical calculations were employed to study the intermediates in the reaction pathways in order to identify the preferred paths for aromatic substitution. In most cases studied para substitution pathways had the lower energy intermediates …