Doctoral theses
Current Record: 201 of 229
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| Identifier |
000032133 |
| Title |
Απομόνωση και χαρακτηρισμός υποσυμπλόκων του πυρήνα του φωτοσυστήματος II των ανωτέρων φυτών και μελέτη του μηχανισμού δράσης αναστολέων |
| Alternative Title |
Isolation and characterization of PhotosystemII-core subcomplexes from higler plants and study of the mode of action of inhibitors |
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Author
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Σπυριδάκη, Ασπασία
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Thesis advisor
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Γανωτάκης, Δημήτριος
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| Abstract |
1. New methods were developed for the purification of several PSII-core subcomplexes in order to study the structure of the photosystem II core. The complexes, which contained the neccesary subunits to carry out the primary charge separation, were the following: a) A complex which contains the proteins: 47 kDa, 32 kDa (D1), 34 kDa (D2), and Cyt b559 b) A complex which contains the above proteins as well as the second interior antenna protein 43 kDa and c) A complex which contains all the proteins required for oxygen evolution (47 kDa, 43 kDa, 32 kDa, 34 kDa, Cyt b559 and 33 kDa) The complexes were isolated by using selective solubilization of Photosystem II with different detergents, ion exchange chromatography and zonal centrifugation. The above complexes were characterized by optical absorption spectroscopy, EPR spectroscopy and were used for three dimensional crystallization trials. The basic parameters which influence membrane protein crystallization were screened. Additionally, the action of histidine (a known oxygen radical scavenger) was examined on PSII-core proteins, in order to stabilize the system. Several crystal forms were obtained and the best crystals were measured by X-ray crystallography. 2. In order to localize the extrinsic proteins, electron microscopy measurements were carried out on solubilized PSII-core complexes, from which these proteins had been selectively extracted. Two dimensional crystals of a PSII-core complex were formed and were analyzed by electron crystallography. Information on the oligomerization state of PSII, the relative assembly and subunit topology was obtained from these studies. 3. A new naturally occuring inhibitor, capsaicin, was found, which has the ability to block the electron transfer of both plant PSII and bacterial RC, at the QB site. The mode of action of capsaicin was investigated by O2 evolution and fluorescence induction measurements in the case of PSII and flash-induced absorbance spectroscopy in the case of the bacterial RC. In the absence of a high resolution structure of PSII, the bacterial RC from Rb. sphaeroides was used as a model for investigating capsaicin binding to the QB-site. X-ray crystallographic analysis of the RC with bound capsaicin provided structural details of capsaicin-protein interactions.
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| Language |
Greek |
| Issue date |
1999-07-01 |
| Collection
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School/Department--School of Sciences and Engineering--Department of Chemistry--Doctoral theses
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Type of Work--Doctoral theses
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| Permanent Link |
https://elocus.lib.uoc.gr//dlib/2/6/c/metadata-dlib-1999spyridaki.tkl
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| Views |
235 |
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