Interactions of low energy electrons with isolated and hydrated biomolecules
Interakce nízkoenergetických elektronů s izolovanými a hydratovanými biomolekulami
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České vysoké učení technické v Praze
Czech Technical University in Prague
Czech Technical University in Prague
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Motivací této práce je lepší pochopení chemických procesu v bunce podstupující ozarování, kdy vzniká velké množství iontu a sekundárních elektronu. Následkem interakcí techto cástic se složkami bunky dochází k poškození bunecných struktur jako jsou DNA, lipidy a proteiny. Cílem práce bylo studium primárních procesu poškození proteinu zárením pomocí metody elektronové záchytové spektroskopie. Tato práce se zameruje na interakce nízkoenergetických elektronu, tedy elektronu s energiemi pri kterých nedochází k ionizaci molekuly, ale k záchytu elektronu (typicky 0 - 10 eV). Pri techto energiích je významný zejména proces disociativního elektronového záchytu, který casto vede k fragmentaci pri subexcitacních energiích. Do práce byly vybrány molekuly loužící jako model pro peptidy. Zvoleny byly dve aminokyseliny L- cystein a L-valin a dva amidy navržené jako jednoduché modely pro peptidovou vazbu: formamid a N-methylacetamid. Tyto slouceniny byly mereny v jejich izolované a klastrové forme. Merení hydratovaných klastru umožnilo studium vlivu okolního prostredí na reakce.
The motivation of this work is a better understanding of the chemical processes in cells undergoing irradiation where a large number of secondary electrons and ions is formed. Many cellular components such as: DNA, lipids (forming membranes) and proteins (performing many vital functions in the cell) get damaged due to the interaction with these products. The aim of this work was to follow the initial damage of proteins using the method of electron capture spectroscopy. This work focuses on low-energy electron-induced reactions, i.e. electrons with energies that do not cause ionisation of molecules but electron capture (typically 0 - 10 eV). These energies are particularly important for the process of dissociative electron capture, that often leads to fragmentation at subexcitation energies. Molecules serving as model compounds for peptides were selected for the work. Four model compounds were selected: two aminoacids L-cysteine, L-valine and two amides proposed as simple models for peptide bonds: formamide, and N-methylacetamide. These molecules were studied in their isolated and cluster forms. The measurement of hydrated clusters enables to examine the effect of the solvent.
The motivation of this work is a better understanding of the chemical processes in cells undergoing irradiation where a large number of secondary electrons and ions is formed. Many cellular components such as: DNA, lipids (forming membranes) and proteins (performing many vital functions in the cell) get damaged due to the interaction with these products. The aim of this work was to follow the initial damage of proteins using the method of electron capture spectroscopy. This work focuses on low-energy electron-induced reactions, i.e. electrons with energies that do not cause ionisation of molecules but electron capture (typically 0 - 10 eV). These energies are particularly important for the process of dissociative electron capture, that often leads to fragmentation at subexcitation energies. Molecules serving as model compounds for peptides were selected for the work. Four model compounds were selected: two aminoacids L-cysteine, L-valine and two amides proposed as simple models for peptide bonds: formamide, and N-methylacetamide. These molecules were studied in their isolated and cluster forms. The measurement of hydrated clusters enables to examine the effect of the solvent.