Dokument: Fluorescence fluctuation-based analysis of the amyloid-beta monomer
| Titel: | Fluorescence fluctuation-based analysis of the amyloid-beta monomer | |||||||
| Weiterer Titel: | Fluoreszenzfluktuationsbasierte Analyse des amyloid-beta monomers | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=37542 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20160329-084534-2 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Dr. Schneider, Mario [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Willbold, Dieter [Gutachter] Prof. Dr. Fitter, Jörg [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 570 Biowissenschaften; Biologie | |||||||
| Beschreibung: | There exists substantial evidence that the amyloid-β (Aβ) peptide plays an important role in the development of Alzheimers’ disease (AD) although the exact molecular mech- anisms are mainly unknown. Aβ can aggregate and from oligomers. Aβ aggregation occurs down to the low-micromolar range which makes conventional techniques such as NMR or X-ray diffraction infeasible.
In this work, fluorescence fluctuation-based methods are applied to explore the struc- tural stability of the Aβ42 monomer, a 42 amino acids long Aβ isoform. Therefore, a cysteine variant of Aβ42 is expressed in E. coli and coupled with a fluorescent dye. Fluorescence-based methods are well-suited to study highly aggregation-prone proteins and peptides since they get along with pico- to nanomolar concentration of sample. This is especially important in the case of Aβ since it occurs in the nanomolar range in vivo. Aβ monomer unfolding is performed in guanidine hydrochloride solutions and detected by fluorescence correlation spectroscopy (FCS). The unfolding curves reveal a two-state cooperative unfolding of the Aβ42 monomer which indicates the presence of stable structural elements. However, the low free energy of the native conformation (≈ 1.8 kcal/mol) indicates a rather low amount of structural elements. Another project included in this thesis deals with the development of a new method to identify fluorescence bursts in single-molecule fluorescence measurements. Fluores- cence bursts arise when single fluorescent molecules traverse a small observation volume of high laser power and subsequently emit bunches of photons (called bursts). A fluo- rescence burst identification is mandatory in order to discriminate background counts from single-molecule transits of fluorescent molecules through the laser beam. Here we present a burst identification method which makes use of all information inherent in time- correlated single photon counting (TCSPC) data, namely micro- and interphoton time information. The method is solely based on probabilities and is called Bayesian burst identification throughout this work. Based on the F-score, it is shown that including both types of time information leads to an improved burst identification performance. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät | |||||||
| Dokument erstellt am: | 29.03.2016 | |||||||
| Dateien geändert am: | 29.03.2016 | |||||||
| Promotionsantrag am: | 11.12.2015 | |||||||
| Datum der Promotion: | 09.02.2016 |
