Zur radiationschemischen Bildung von Aminosäuren durch Carboxylierung und Aminierung

1968 ◽  
Vol 23 (5) ◽  
pp. 581-587 ◽  
Author(s):  
Klaus Dose ◽  
Sergio Risi
Keyword(s):  
Amino Acids ◽  
Energy Transfer ◽  
Carboxylic Acids ◽  
Reaction Mechanisms ◽  
Linear Energy Transfer ◽  
Amino Groups ◽  
Primitive Earth ◽  
Unusual Amino Acids ◽  
X Ray ◽  
Low Probability

The formation of aliphatic α-amino acids by X-ray induced carboxylation of simple amines or amination of simple carboxylic acids is not favored over the formation of other amino acids. The new carboxylic and amino groups are more or less distributed statistically over the carbon atoms of the starting material. On radiationchemical formation of aliphatic hydrocarbons over C3, therefore, an increasing amount of unusual amino acids is produced. The results are influenced by various parameters such as temperature, pH, concentration, linear energy transfer and total dosis of radiation applied. Also peptides can be formed radiationchemically. However, the formation of greater molecules by radiationchemical processes under the conditions of a primitive earth seems to have only a low probability. The reaction mechanisms of radiationchemical carboxylation and amination are discussed.

scholarly journals The effect of low LET (Linear Energy Transfer) ionizing radiation to catalase activity of wistar’s submandibular gland

2016 ◽  
Vol 1 (3) ◽  
pp. 145
Author(s):  
Nevy T. Putri ◽  
Sarianoferni Sarianoferni ◽  
Endah Wahjuningsih
Keyword(s):  
Energy Transfer ◽  
Ionizing Radiation ◽  
Submandibular Gland ◽  
Rattus Norvegicus ◽  
Catalase Activity ◽  
Linear Energy Transfer ◽  
Submandibular Salivary Gland ◽  
X Rays ◽  
X Ray ◽  
Bonferroni Test

Intraoral periapical radiograph examination is the additional examination which is the most widely used in Dentistry. This radiograph examination using an x-ray ionizing radiation with low LET (Linear Energy Transfer), and may affect submandibular salivary gland. Ionizing radiation exposure can cause damage by inducing a series of changes at the molecular and cellular level. This study aimed to prove the effects of x-ray ionizing radiation with low LET towards the catalase activity of Rattus norvegicus strain Wistar’s submandibular gland. The subjects were 28 male Wistar rats and divided into 4 groups (n=7). Three groups were exposed 4, 8 and 14 times to radiation with 0.002 µSv for each exposure. The catalase activity of each rat was examined by a spectrophotometer. Data were analyzed using one-way ANOVA followed by Bonferroni test. The results showed the average of catalase activity on Wistar rat’s submandibular gland, respectively for: 0.150±0.0895 (KK), 0.1405±0.0607 (K1), 0.1228±0.0290 (K2), 0.1227±0.0556 (K3). Data showed significant differences of catalase activity between test groups, but showed not significant differences of catalase activity between each groups of Rattus norvegicus strain Wistar’s submandibular gland. In this study concluded decreased catalase activity of Rattus norvegicus strain Wistar’s submandibular gland resulting from x-rays ionizing radiation by 4 times, 8 times and 14 times exposures.

scholarly journals Relating Linear Energy Transfer to the Formation and Resolution of DNA Repair Foci After Irradiation with Equal Doses of X-ray Photons, Plateau, or Bragg-Peak Protons

2018 ◽  
Vol 19 (12) ◽  
pp. 3779 ◽  
Author(s):  
Sebastian Oeck ◽  
Klaudia Szymonowicz ◽  
Gesa Wiel ◽  
Adam Krysztofiak ◽  
Jamil Lambert ◽  
...  
Keyword(s):  
Dna Damage ◽  
Energy Transfer ◽  
Linear Energy Transfer ◽  
Bragg Peak ◽  
Cultured Cells ◽  
Human Cancer ◽  
Proton Beam Therapy ◽  
X Ray ◽  
Cellular Repair ◽  
Set Up

Proton beam therapy is increasingly applied for the treatment of human cancer, as it promises to reduce normal tissue damage. However, little is known about the relationship between linear energy transfer (LET), the type of DNA damage, and cellular repair mechanisms, particularly for cells irradiated with protons. We irradiated cultured cells delivering equal doses of X-ray photons, Bragg-peak protons, or plateau protons and used this set-up to quantitate initial DNA damage (mainly DNA double strand breaks (DSBs)), and to analyze kinetics of repair by detecting γH2A.X or 53BP1 using immunofluorescence. The results obtained validate the reliability of our set-up in delivering equal radiation doses under all conditions employed. Although the initial numbers of γH2A.X and 53BP1 foci scored were similar under the different irradiation conditions, it was notable that the maximum foci level was reached at 60 min after irradiation with Bragg-peak protons, as compared to 30 min for plateau protons and photons. Interestingly, Bragg-peak protons induced larger and irregularly shaped γH2A.X and 53BP1 foci. Additionally, the resolution of these foci was delayed. These results suggest that Bragg-peak protons induce DNA damage of increased complexity which is difficult to process by the cellular repair apparatus.

scholarly journals Degradation of 4-Chlorophenol by Gamma Radiation of 137Cs and X-rays

2019 ◽  
Vol 54 (3) ◽  
Author(s):  
Julio César González-Juárez ◽  
Jaime Jiménez-Becerril ◽  
Jesús Cejudo-Álvarez
Keyword(s):  
Energy Transfer ◽  
Gamma Radiation ◽  
Crystalline Structure ◽  
Linear Energy Transfer ◽  
The Other ◽  
X Rays ◽  
137Cs Source ◽  
X Ray ◽  
Radiolytic Degradation ◽  
Radiation Sources

This paper presents results of radiolytic degradation of 4-chlorophenol in the presence of TiO2, Al2O3, y SiO2, using different radiation sources than 60Co, which is so common in this type of experiment. The radiation sources used were X-rays with energy of 100 keV and radiation from 137Cs (662 keV). After irradiation with a dose of 50 cGy X-ray and TiO2 obtained a degradation of about 5%, no degradation was obtained with 137Cs source and other oxides. This may be due to the fact that X-rays have a linear energy transfer (LET) greater value, and in the case of TiO2 present a crystalline structure, whereas the other two oxides are amorphous. Both characteristics result in better formation of a reactive species that allows the degradation of the compound.

scholarly journals Ancestral L-amino acid oxidases for deracemization and stereoinversion of amino acids

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Shogo Nakano ◽  
Kohei Kozuka ◽  
Yuki Minamino ◽  
Hiroka Karasuda ◽  
Fumihito Hasebe ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Protein Engineering ◽  
Crystal Structures ◽  
Reaction Mechanisms ◽  
Molecular Level ◽  
Substrate Recognition ◽  
Engineering Method ◽  
Substrate Selectivity ◽  
X Ray

AbstractL-amino acid oxidases (LAAOs) can be applied to convert racemic amino acids to D-isomers, which are potential precursors of pharmaceuticals. However, this application is hampered by the lack of available stable and structure-determined LAAOs. In this study, we attempt to address this limitation by utilizing two ancestral LAAOs: AncLAAO-N4 and AncLAAO-N5. AncLAAO-N4 has the highest thermal and temporal stabilities among the designed LAAOs that can be used for deracemization and stereoinversion. AncLAAO-N5 can provide X-ray crystal structures, which are helpful to reveal substrate recognition and reaction mechanisms of LAAOs at the molecular level. Next, we attempted to improve activity of AncLAAO-N4 toward L-Val through a semi-rational protein engineering method. Three variants with enhanced activity toward L-Val were obtained. Taken together, we believe that the activity and substrate selectivity of AncLAAOs give them the potential to be key enzymes in various chemoenzymatic reactions.

Monte Carlo simulation of the radiolysis of the ceric sulfate dosimeter by low linear energy transfer radiation

2012 ◽  
Vol 90 (9) ◽  
pp. 717-723 ◽  
Author(s):  
Ianik Plante ◽  
Thititip Tippayamontri ◽  
Narongchai Autsavapromporn ◽  
Jintana Meesungnoen ◽  
Jean-Paul Jay-Gerin
Keyword(s):  
Energy Transfer ◽  
Reaction Mechanisms ◽  
Linear Energy Transfer ◽  
Acidic Medium ◽  
Sulfate Solution ◽  
Oh Radicals ◽  
Chemical Reaction Kinetics ◽  
Initial Concentration ◽  
Ceric Sulfate ◽  
Linear Energy Transfer Radiation

The ceric sulfate dosimeter is based on the radio-induced reduction of Ce4+ in acidic medium. For low linear energy transfer (LET) radiation, the yield of Ce3+ is 2.4 molecules / 100 eV, regardless of the presence of oxygen. To investigate the reaction mechanisms of the ceric sulfate dosimeter, we simulated the chemical reaction kinetics curves and the evolution of G(Ce3+), G(O2), and G(H2) in the ceric sulfate solution with and without oxygen. Studies of G(Ce3+) as function of the initial concentration of Ce3+ and of the LET were also done. One important finding of this study is that •OH radicals are scavenged by the reaction •OH + HSO4– → SO4•– + H2O, rather than by the reaction •OH + Ce3+ → Ce4+ + OH–.

X-Ray Microanalysis of Nickel and Cobalt Intensified Peroxidase- Antiperoxidase For Verification of Reaction Sites

1985 ◽  
Vol 43 ◽  
pp. 468-469
Author(s):  
A. Angel ◽  
K. Miller ◽  
V. Seybold ◽  
R. Kriebel
Keyword(s):  
Reaction Mechanisms ◽  
Visual Discrimination ◽  
Osmium Tetroxide ◽  
Ultrastructural Level ◽  
Microscopic Level ◽  
Electron Microscopic Level ◽  
Electron Microscopic ◽  
X Ray ◽  
Insoluble Polymer ◽  
Cytochemical Reaction

Localization of specific substances at the ultrastructural level is dependent on the introduction of chemicals which will complex and impart an electron density at specific reaction sites. Peroxidase-antiperoxidase(PAP) methods have been successfully applied at the electron microscopic level. The PAP complex is localized by addition of its substrate, hydrogen peroxide and an electron donor, usually diaminobenzidine(DAB). On oxidation, DAB forms an insoluble polymer which is able to chelate with osmium tetroxide becoming electron dense. Since verification of reactivity is visual, discrimination of reaction product from osmiophillic structures may be difficult. Recently, x-ray microanalysis has been applied to examine cytochemical reaction precipitates, their distribution in tissues, and to study cytochemical reaction mechanisms. For example, immunoreactive sites labelled with gold have been ascertained by means of x-ray microanalysis.

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