Cel The objective of this project is to provide an experimental basis for determination of factors that contribute to the regulation of electron and proton transfer in photosynthetic electron transfer chains of chloroplasts and cyanobacteria. The research programme is subdivided into three parts:1. Investigation of the relative contribution of transmembrane electric potential (??) and pH gradient (?pH) to the overall electrochemical proton gradient in model systems and chloroplasts under various experimental conditions. The major tasks include development of model systems appropriate for measurements of steady-state levels of ?? and ?pH.This implies:a) isolation of the functionally-active photosystem I (PS I), photosystem II (PS II), and bf-complexes as well as cytochrome c6 and plastocyanin from higher plants and cyanobacteria;b) incorporation of the isolated pigment protein complexes into proteoliposomes and testing the activity of PS II oxygen-evolving complex by conventional polarography and by EPR spectrometry using microscopic spin-label probes;c) estimation of the steady-state levels of the light-induced ?? And ?pH generation in hybrid proteoliposomes, containing either PS I and bf, or PS II and bf-complexes by direct electrometrical technique and pH-sensitive EPR spin-probes and study of the effects of pH, ionic strength, buffer capacity and viscosity on relative contribution of ?? and ?pH components to the overall ?µH+ generated in two hybrid systems;d) comparison of the light-induced ?pH steady-state levels in thylakoids and hybrid proteoliposomes;2. Detection of the transient plastosemiquinone radicals in PS II, PS I and bf-complexes during flash-induced single turnovers using high field/ high frequency EPR spectroscopy. Elucidation of possible light-induced conformational changes of the QA-. site with respect to P680+.as compared to the ground state configuration P680QA in PS II complexes and of the Qi- state in the bf-complex by time-resolved W-band EPR spectroscopy. Elucidation of the nature of electrogenic reactions associated with semiquinone-anion Qi- generation and decay at the quinone-reductase site of the bf-complex by direct electrometrical technique;3. Determination of the factors responsible for the control of reduction potential of the iron-sulfur cluster FX in the PS I complex. Measurement of redox midpoint potential of the iron-sulfur cluster FX in the whole and FA/FB-lacking PS I complexes using cyclic voltammetry Testing of possible changes in dielectric properties and molecular mobility of the protein vicinity of the FX cluster in PS I complex induced by removal of extrinsic PsaC subunit using doxyl stearate spin labels. Calculation of the relative contribution of various factors to the midpoint potential of FX based on the recently available 3D structure of PS I at 2.5 Å resolution.The group of teams, although having a common interest in study of molecular mechanisms of charge transfer in photosynthesis, has very different types of expertise and, together, offer a unique combined approach to this research. The expertise of the Team in Baku is in biochemistry of photosynthetis, including isolation, stabilization and functional characterization of pigment-protein complexes by polarography, steady-state absorbance and fluorescence spectroscopy. The Moscow Team (A.N. Belozersky Institute of Physico-Chemical Biology) has expertise in study of functional activity of the model systems by flash-induced optical spectrometry and direct electrometry. The Italian Team members are experts in bioinorganic chemistry of paramagnetic metalloproteins, including isolation of soluble metalloproteins, direct electrochemical measurements of reduction potentials and NMR spectroscopy. The expertise of the Berlin Team is in high-field/high frequency EPR- and ENDOR- spectroscopies, both in their cw and pulsed modes of operation. The second Moscow Team (Faculty of Physics, Moscow State University) is specialized on the application of spin-probes to study the light-induced pH gradients, oxygen evaluation and dynamic properties and structural organization of memranes.The expected outcomes of this study include both answers to a number of specific questions in molecular mechanisms of charge transfer by photosynthetic pigment-protein complexes and, on a broader base, the mechanisms of electron and proton transfer control in chloroplasts. Program(-y) IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993- Temat(-y) 4 - Life Sciences OPEN - OPEN Call Zaproszenie do składania wniosków Data not available System finansowania Data not available Koordynator University of Bologna Wkład UE Brak danych Adres Viale Berti Pichat 40127 Bologna Włochy Zobacz na mapie Koszt całkowity Brak danych Uczestnicy (4) Sortuj alfabetycznie Sortuj według wkładu UE Rozwiń wszystko Zwiń wszystko Academy of Sciences of Azerbaijan Azerbejdżan Wkład UE Brak danych Adres Metbuat ave, 2 370073 Baku Zobacz na mapie Koszt całkowity Brak danych Freie Universität Berlin Niemcy Wkład UE Brak danych Adres Arnimallee, 14 14195 Berlin Zobacz na mapie Koszt całkowity Brak danych M.V. Lomonosov Moscow State University Rosja Wkład UE Brak danych Adres Vorobjovy gory 119899 Moscow Zobacz na mapie Koszt całkowity Brak danych M.V. Lomonosov Moscow State University Rosja Wkład UE Brak danych Adres Vorobjovy Gory 119899 Moscow Zobacz na mapie Koszt całkowity Brak danych
