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You searched for +publisher:"Freie Universität Berlin" +contributor:("Prof. Dietmar Stehlik"). Showing records 1 – 2 of 2 total matches.

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Freie Universität Berlin

1. Heyne, Karsten. Ultrafast dynamic protein-controlled reactions in bacteriorhodopsin and bacterial phytochrome.

Degree: 2002, Freie Universität Berlin

In nature chromoproteins facilitate conversion of light to biochemical energy. Thereby the specific embedding of the light absorbing chromophore in the protein binding pocket is crucial for controlling the yield and the reaction channels of light conversion. In order to understand this optimized photoreaction, we examine the impact of chromophore - protein interaction on the primary photoreaction, e. g. the femtosecond to picosecond time span the photon is absorbed and first ground state intermediates arise. In this work two biological important chromoproteins are studied: 1) Bacteriorhodopsin (bR) is a light driven proton-pump, which enables the bacterium to produce ATP and prevent from starvation by lack of energy. The primary step of light conversion is the trans-to-cis isomerization of the retinal chromophore. The dynamic of this photoreaction is catalyzed at least by a factor of 3 due to the chromophore - protein interaction in comparison to the same reaction in solution. The quantum yield is drastically increased and due to the protein all other reaction channels are suppressed. We explore specific single and double mutants to find a crucial or minimal binding pocket for the catalytic reaction. 2) Bacterial phytochrome from Cyanobacterium Synechocystis (Cph1) is discovered only a few years ago and shows large genetic homology to phytochrome of plants. Spectroscopic features are similar, so that comparison of the two phytochromes give more insight in function and chromophore - protein interaction of phytochromes. Characteristic feature of phytochromes are two thermally stable states, which show different photoreactions in the same protein binding pocket. We characterize the primary photoreaction of Cph1 and propose a model with a distribution of potential surfaces to explain our data and in respect of published data. Advisors/Committee Members: n (gender), Prof. Dietmar Stehlik (firstReferee), Prof. Maarten Heyn (furtherReferee).

Subjects/Keywords: bacteriorhodopsin; phytochrome; reaction control; isomerization; ultrafast reaction; 500 Naturwissenschaften und Mathematik::530 Physik::530 Physik

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APA (6th Edition):

Heyne, K. (2002). Ultrafast dynamic protein-controlled reactions in bacteriorhodopsin and bacterial phytochrome. (Thesis). Freie Universität Berlin. Retrieved from http://dx.doi.org/10.17169/refubium-8029

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Heyne, Karsten. “Ultrafast dynamic protein-controlled reactions in bacteriorhodopsin and bacterial phytochrome.” 2002. Thesis, Freie Universität Berlin. Accessed August 04, 2020. http://dx.doi.org/10.17169/refubium-8029.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Heyne, Karsten. “Ultrafast dynamic protein-controlled reactions in bacteriorhodopsin and bacterial phytochrome.” 2002. Web. 04 Aug 2020.

Vancouver:

Heyne K. Ultrafast dynamic protein-controlled reactions in bacteriorhodopsin and bacterial phytochrome. [Internet] [Thesis]. Freie Universität Berlin; 2002. [cited 2020 Aug 04]. Available from: http://dx.doi.org/10.17169/refubium-8029.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Heyne K. Ultrafast dynamic protein-controlled reactions in bacteriorhodopsin and bacterial phytochrome. [Thesis]. Freie Universität Berlin; 2002. Available from: http://dx.doi.org/10.17169/refubium-8029

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Freie Universität Berlin

2. Byrdin, Martin. Measuring and Modeling Excitation Dynamics in Photosystem I.

Degree: 2000, Freie Universität Berlin

In this work, dynamics of excitation energy transfer and decay in a cyanobacterial PS I core antenna-RC-complex from Synechococcus el. is studied combining fluorescence induction techniques with picosecond fluorescence lifetime measurements at temperatures between 5 K and 300 K with special attention to the oxidation state of the primary donor P700. The measured fluorescence behaviour is modeled by simulations of the excited state transfer and decay based on structral and spectral information. For the first time, a difference in the quenching efficiency of the PS I core- antenna-RC-complex with open vs. closed RC was resolved both by fluorescence induction and ps- fluorescence as well as by quasi steady state spectroscopy. As the form of the steady state spectra at RT is (nearly) identical, the found difference of 12┬▒ 5 % in fluorescence yield is not due to spectral differences between the open and closed RC states but to a ~3 ps difference in the overall excitation decay lifetime. Thus, in closed PS I the excited state is quenched slightly worse than in open PS I. Time-resolved fluorescence could resolve non-conservative transfer spectra both at RT and at 5 K, indicating that the quenched state of the complex is not fully equilibrated. As a consequence, trap limitation of the excited state kinetics can be excluded. From the excited state lifetime at 5 K in closed PS I complexes a A720-P700 distance of ~3.5 nm is calculated. The observed inter-monomer exchange of excitation energy suggests the localization of some A720 pigments in the connecting domain of the trimeric unit. Structural/spectral information based simulation of the excited state dynamics reveales the necessiety for some A708 pigments to be placed next to the RC domain to increase the transient population of P700. The kinetics observed on a model with such arrangement of the red pigments yields optimal parameters as an intrinsic charge separation rate constant of (0.5 ps)-1 and a F├Ârster radius of 7.3 nm for the reproduction of the measured fluorescence. Above that, the simulation shows an equilibration pertubation over the whole red wing of the emission and the determining influence of the red pigments. The kinetics in closed PS I can be described by fast quenching via internal conversion if the non-oxidized P700 Chl is set to maximal absorption at 685 nm. Testing the influence of the various parameters leads to the conclusion that for open PS I, the observable excited state decay is characterized by well-balanced kinetics rather than limiting cases. Advisors/Committee Members: n (gender), Prof. Dietmar Stehlik (firstReferee), Prof. Marten Heyn (furtherReferee).

Subjects/Keywords: photosynthesis; time resolved fluorescence; computer simulation; excitation dynamics; photosystem I; 87.15-v; 87.64Aa; 87.64Ni; 31.70Hq; 82.20Rp; 500 Naturwissenschaften und Mathematik::530 Physik::530 Physik

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Byrdin, M. (2000). Measuring and Modeling Excitation Dynamics in Photosystem I. (Thesis). Freie Universität Berlin. Retrieved from https://refubium.fu-berlin.de/handle/fub188/12094

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Byrdin, Martin. “Measuring and Modeling Excitation Dynamics in Photosystem I.” 2000. Thesis, Freie Universität Berlin. Accessed August 04, 2020. https://refubium.fu-berlin.de/handle/fub188/12094.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Byrdin, Martin. “Measuring and Modeling Excitation Dynamics in Photosystem I.” 2000. Web. 04 Aug 2020.

Vancouver:

Byrdin M. Measuring and Modeling Excitation Dynamics in Photosystem I. [Internet] [Thesis]. Freie Universität Berlin; 2000. [cited 2020 Aug 04]. Available from: https://refubium.fu-berlin.de/handle/fub188/12094.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Byrdin M. Measuring and Modeling Excitation Dynamics in Photosystem I. [Thesis]. Freie Universität Berlin; 2000. Available from: https://refubium.fu-berlin.de/handle/fub188/12094

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.