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31.
32.
Three thylakoid complexes were isolated by deoxycholate preparative electrophoresis. The protein composition of each fraction was analyzed by SDS analytical electrophoresis. No protein of the PS 1 enriched fraction (fraction 1) was found in the PS 2 enriched fraction (fraction 2) and inversely. The antenna complex (fraction 3) did not have any contamination by proteins of fraction 1 or fraction 2. Fraction 1 was mainly composed of the CP1, the reaction center complex of the PS1, and by low molecular weight proteins, previously found in other PS 1 preparations. Tentative assignments of these proteins are presented; among them are iron sulfur proteins. After analytical SDS electrophoresis of fraction 2, the reaction center complex was dissociated. Nevertheless three proteins of 50 kD, 42 kD and 35 kD were assigned to this complex. Fraction 2 contained also the three cytochromes of the thylakoid membranes: cyt f, cyt b6, cyt b559. Fraction 3 was exclusively composed of one protein pigment complex, CP2.Abbreviations SDS
sodium dodecyl sulfate
- PS 1
photosystem 1
- PS 2
photosystem 2
- CP1, CP2
protein pigment complexes isolated by SDS electrophoresis
- cyt
cytochromes
- P700
primary electron donor of PS 1
- P680
primary electron donor of PS 2
- DOC
deoxycholate
- Q
primary plastoquinone electron acceptor
- CF
coupling factor 相似文献
33.
Transient complexes of redox proteins: structural and dynamic details from NMR studies 总被引:1,自引:0,他引:1
Redox proteins participate in many metabolic routes, in particular those related to energy conversion. Protein-protein complexes of redox proteins are characterized by a weak affinity and a short lifetime. Two-dimensional NMR spectroscopy has been applied to many redox protein complexes, providing a wealth of information about the process of complex formation, the nature of the interface and the dynamic properties of the complex. These studies have shown that some complexes are non-specific and exist as a dynamic ensemble of orientations while in other complexes the proteins assume a single orientation. The binding interface in these complexes consists of a small hydrophobic patch for specificity, surrounded by polar, uncharged residues that may enhance dissociation, and, in most complexes, a ring or patch of charged residues that enhances the association by electrostatic interactions. The entry and exit port of the electrons is located within the hydrophobic interaction site, ensuring rapid electron transfer from one redox centre to the next. 相似文献
34.
Arnesano F Banci L Bertini I Van Der Wetering K Czisch M Kaptein R 《Journal of biomolecular NMR》2000,17(4):295-304
15N-1H 1J couplings were measured at 500 MHz and 800 MHz for 15N enriched oxidized cytochrome b
562 from E. coli. The magnetic field dependence of 70 1J values, which could be measured without signal overlap, shows that there is a molecular magnetic anisotropy which provides partial molecular orientation in the magnetic field and, consequently, residual dipolar couplings (rdc). The rdc were used as further constraints to improve the existing structure [Arnesano et al. (1999) Biochemistry, 38, 8657–8670] with a protocol which uses the rhombic anisotropy [Banci et al. (1998) J. Am. Chem. Soc., 120, 12903–12909]. The overall large molecular magnetic anisotropy has been found to be determined by both the low spin iron (III) and the four helix bundle structure magnetic susceptibility anisotropy contributions. 相似文献
35.
Chávez-Pacheco JL Martínez-Yee S Contreras ML Gómez-Manzo S Membrillo-Hernández J Escamilla JE 《Journal of applied microbiology》2005,99(5):1130-1140
AIMS: Gluconacetobacter xylinum is well known for its ability to produce large amounts of cellulose, however, little is known about its cell physiology. Our goal was to study the respiratory metabolism and components of the respiratory system of this bacterium in static cultures. To reach our goal, a medium formulation had to be designed to improve cell growth and cellulose production together with a novel method for the recovery of cells from cellulose pellicles. METHODS AND RESULTS: Successive modifications of a nutrient medium improved G. xylinum cell growth 4.5-fold under static culture conditions. A blender homogenization procedure for the releasing of cells from the cellulose matrix gave a high yield of cells recovered. Respiratory activities of purified cells were greatly stimulated by exogenous substrates and showed to be resistant to KCN. Unexpectedly, exogenous NADH was oxidized at high rates. Cytochromes a, b, c and d were identified after spectral analyses. CONCLUSIONS: Partial bioenergetic characterization of G. xylinum cells allowed us to propose a scheme for its respiratory system. In addition, the growth medium for biomass production and the procedure for the efficient recovery of cells from cellulose pellicles were significantly improved. SIGNIFICANCE AND IMPACT OF THE STUDY: This work provides the first-ever bioenergetic characterization of G. xylinum grown in static cultures. In addition, a novel methodology to obtain purified cells in suitable quantities for biochemical research is described. 相似文献
36.
Il'chenko A. P. Chernyavskaya O. G. Shishkanova N. V. Finogenova T. V. 《Microbiology》2001,70(2):151-157
The comparative studies performed in this work showed that overproduction of -ketoglutaric acid (KGA) and citric acid (CA) from ethanol by the mutantYarrowia lipolyticastrain 1 requires both a deficiency of thiamine and a relatively high concentration of ammonium ions in the medium, whereas CA overproduction requires an almost zero concentration of ammonium ions. The threshold value of the dissolved oxygen concentration in the medium, pO2, for CA overproduction is considerably higher than for KGA overproduction. The respiration rate of CA-overproducing cells was 2–3.5 times higher than that of KGA-overproducing cells. The main terminal electron carrier functioning in the KGA-overproducing cells was cytochrome oxidase. In the CA-overproducing cells, the main terminal oxidase was presumably o-type cytochrome. 相似文献
37.
Rates of thermoinduced conformational transitions of reaction center (RC) complexes providing effective electron transport were studied in chromatophores and isolated RC preparations of various photosynthesizing purple bacteria using methods of fast freezing and laser-induced temperature jump. Reactions of electron transfer from the primary to secondary quinone acceptors and from the multiheme cytochrome c subunit to photoactive bacteriochlorophyll dimer were used as probes of electron transport efficiency. The thermoinduced transition of the acceptor complex to the conformational state facilitating electron transfer to the secondary quinone acceptor was studied. It was shown that neither the characteristic time of the thermoinduced transition within the temperature range 233-253 K nor the characteristic time of spontaneous decay of this state at 253 K exceeded several tens of milliseconds. In contrast to the quinone complex, the thermoinduced transition of the macromolecular RC complex to the state providing effective electron transport from the multiheme cytochrome c to the photoactive bacteriochlorophyll dimer within the temperature range 220-280 K accounts for tens of seconds. This transition is thought to be mediated by large-scale conformational dynamics of the macromolecular RC complex. 相似文献
38.
Cooperative interaction of the high-potential hemes (Ch) in the cytochrome subunit of the photosynthesizing bacterium Ectothiorhodospira shaposhnikovii was studied by comparing redox titration curves of the hemes under the conditions of pulse photoactivation inducing single
turnover of electron-transport chain and steady-state photoactivation, as well as by analysis of the kinetics of laser-induced
oxidation of cytochromes by reaction center (RC). A mathematical model of the processes of electron transfer in cytochrome-containing
RC was considered. Theoretical analysis revealed that the reduction of one heme Ch facilitated the reduction of the other heme, which was equivalent to a 60 mV positive shift of the midpoint potential. In
addition, reduction of the second heme Ch caused a three-to four-fold acceleration of the electron transfer from the cytochrome subunit to RC.
Published in Russian in Biokhimiya, 2007, Vol. 72, No. 11, pp. 1540–1547. 相似文献
39.
40.
M. Santos M.M. Correia dos Santos M.L. Simes Gonalves C. Costa J.C. Romo J.J.G. Moura 《Journal of inorganic biochemistry》2006,100(12):2009
Desulfovibrio vulgaris Hildenborough cytochrome c3 contains four hemes in a low-spin state with bis-histidinyl coordination. High-spin forms of cytochrome c3 can be generated by protonation of the axial ligands in order to probe spin equilibrium (low-spin/high-spin). The spin alterations occurring at acid pH, the associated changes in redox potentials, as well as the reactivity towards external ligands were followed by the conjunction of square wave voltammetry and UV–visible, CD, NMR and EPR spectroscopies. These processes may be used for modelling the action of enzymes that use spin equilibrium to promote enzyme activity and reactivity towards small molecules. 相似文献