Dokument: The Structure of the Water Oxidizing Complex of Photosystem II and the Sites of Substrate Binding as Investigated by Pulse EPR Spectroscopy

Titel:	The Structure of the Water Oxidizing Complex of Photosystem II and the Sites of Substrate Binding as Investigated by Pulse EPR Spectroscopy
URL für Lesezeichen:	https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=22922
URN (NBN):	urn:nbn:de:hbz:061-20121022-101108-1
Kollektion:	Dissertationen
Sprache:	Englisch
Dokumententyp:	Wissenschaftliche Abschlussarbeiten » Dissertation
Medientyp:	Text
Autor:	Dr. Rapatskiy, Leonid [Autor]
Dateien:	[Dateien anzeigen] Adobe PDF [Details] 14,10 MB in einer Datei [ZIP-Datei erzeugen] Dateien vom 18.10.2012 / geändert 18.10.2012
Beitragende:	Prof. Dr. Lubitz, Wolfgang [Gutachter] Prof. Dr. Schierbaum, Klaus [Gutachter]
Dewey Dezimal-Klassifikation:	500 Naturwissenschaften und Mathematik » 530 Physik
Beschreibung:	The work performed in this thesis aimed to resolve several key functions of the photosystem II (PS II) enzyme, in particular the structure and mechanism of the water oxidizing complex (WOC). Advanced electron paramagnetic resonance (EPR) methodologies were employed to provide detailed atomic level information about the complex and its reaction (S-state) cycle. A strong emphasis was placed on determining the sites of substrate water binding. Topics addressed in this thesis include the following: 1) Resolution of the site(s) of substrate binding. A direct probe for water derived ligands via the detection of labeled substrates with the 17O isotope was developed that allowed an assignment of one of the substrate sites of the WOC. This substrate site, generally termed ‘the slow substrate’ likely represents a bridging ligand (µ-oxo) ligand throughout most of the reaction cycle. 2) The role of the Ca2+ ion of the WOC, as probed by replacing the Ca2+ ion with Sr2+ biosynthetically. Multi-frequency EPR and electron nuclear double resonance (ENDOR) data demonstrate Ca/Sr substitution has little effect on the electronic properties of the WOC. Together with density functional theory (DFT) calculations, these measurements further refine models of the geometric structure of the WOC and assign specific oxidation states the four manganese ions. 3) Variation in the structure and coordinating residues of the WOC across different species and the influence of small, substrate analogues such as methanol. It is suggested that the underlying cause of these variations is the flexibility of µ-oxo bridge connecting the dangler Mn ion and Mn3 cuboidal unit, which leads to distortions of ligand arrangement in the vicinity of the WOC. 4) Benchmarking of all experimental data collected in biological systems to inorganic model complexes. Models have well defined geometry in which particular structural features can be examined in depth. Broken symmetry DFT calculations performed in tandem on such model complexes allow further insight to be ascertained as to the parameters which lead to certain molecular arrangements within metallocofactors.
Lizenz:	Urheberrechtsschutz
Fachbereich / Einrichtung:	Mathematisch- Naturwissenschaftliche Fakultät » WE Physik
Dokument erstellt am:	22.10.2012
Dateien geändert am:	22.10.2012
Promotionsantrag am:	09.05.2012
Datum der Promotion:	12.06.2012