共查询到20条相似文献,搜索用时 15 毫秒
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C. Babin 《Marine Micropaleontology》1986,10(4)
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A new high-yield preparative route to (por)Ru(NO)Cl compounds (por = porphyrinato dianion) from reactions of (por)Ru(NO)(alkoxide) precursors with boron trichloride is reported. These ruthenium nitrosyl chloride complexes are known to be useful precursors to (por)Ru(NO)-containing derivatives. The crystal structure of (OEP)Ru(NO)Cl (OEP = octaethylporphyrinato dianion) shows that the RuNO linkage is linear. The redox behavior of the (por)Ru(NO)Cl compounds has been determined by cyclic voltammetry. Analysis of the data reveals that the first oxidation of the (por)Ru(NO)Cl compounds is porphyrin-ring centered. 相似文献
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Studies reported here were undertaken to gain greater molecular insight into the complex structure of mitochondrial ATP synthase (F(0)F(1)) and its relationship to the enzyme's function and motor-related properties. Significantly, these studies, which employed N-terminal sequence, mass spectral, proteolytic, immunological, and functional analyses, led to the following novel findings. First, at the top of F(1) within F(0)F(1), all six N-terminal regions derived from alpha + beta subunits are shielded, indicating that one or more F(0) subunits forms a "cap." Second, at the bottom of F(1) within F(0)F(1), the N-terminal region of the single delta subunit and the C-terminal regions of all three alpha subunits are shielded also by F(0). Third, and in contrast, part of the gamma subunit located at the bottom of F(1) is already shielded in F(1), indicating that there is a preferential propensity for interaction with other F(1) subunits, most likely delta and epsilon. Fourth, and consistent with the first two conclusions above that specific regions at the top and bottom of F(1) are shielded by F(0), further proteolytic shaving of alpha and beta subunits at these locations eliminates the capacity of F(1) to couple a proton gradient to ATP synthesis. Finally, evidence was obtained that the F(0) subunit called "F(6)," unique to animal ATP synthases, is involved in shielding F(1). The significance of the studies reported here, in relation to current views about ATP synthase structure and function in animal mitochondria, is discussed. 相似文献
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Lei Li 《Inorganica chimica acta》2010,363(4):748-55
Three Cd (II)-M (II) hetero-nuclear coordination polymers, [FeCd2(Hcit)2(H2O)2]n (1), [CoCd2(BTC)2(H2O)4]n (2) and [Cd3(Hcit)2(H2O)2]n (3) (H4cit = citric acid, H3BTC = 1,3,5-benzenetricarboxyl acid), were synthesized through hydrothermal method. They were characterized through elemental analysis, IR spectra, UV-Vis absorption spectra, X-ray powder diffraction, single-crystal X-ray diffraction and surface photovoltage spectra (SPS). Structural analysis indicates that 1 and 3 possess 2D structures, which are further connected to 3D structures by hydrogen bonds. 2 is a 3D Cd-Co coordination polymer bridged by BTC3− groups. The SPS show that 1 and 2 present positive photovoltage response in 300-550 nm, but the photovoltage response of 3 appears in 300-400 nm. It is indicated that the limits of SPS response bands of polymers 1 and 2 are wider than those of 3 because of introduction of the other transition metal ions. There is a good corresponding relationship between SPS and UV-Vis absorption spectra. 相似文献
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F. Cristiani D. De Filippo P. Deplano F. Devillanova A. Diaz E.F. Trogu G. Verani 《Inorganica chimica acta》1975,12(1):119-122
Complexes of the type M(CO)3(22cy), where M = Cr, Mo, W and 22cy = 2,2-para-cyclophane were prepared and characterised. The i.r., p.m.r., mass spectrography spectra are discussed. The Mo derivative decomposes in solution giving 22cy, Mo(CO)6 and Mo, according to a first order mechanism. 相似文献
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Summary Subunit III and c, the 8 kDa components of the chloroplast CF0, andE. coli H+ channel complexes respectively, were isolated and purified for the purpose of studying their Ca++-binding properties. Purified subunit III or c as well as the unfractionated organic-solvent soluble preparation from chloroplasts were used in a45Ca++-ligand blot assay known to detect high affinity Ca++-binding sites in proteins. Both subunit III and c showed strong45Ca++-binding. None of the other CF0 subunits bound Ca++ and of the CF1 only a weak binding was detected in the region of the , subunits. The Ca++-binding was inhibited after treating the proteins in solution by derivatizing aqueously exposed carboxyl groups with a water soluble carbodiimide plus a nucleophile, after de-formylation of the N-terminal methionine, or with a subsequent treatment with La3+. Dicyclohexylcarbodiimide treatment (no nucleophile was added) of thylakoid membranes, which derivatizes the hydrophobically located Glu 61 (Asp 61 inE. coli), did not inhibit the Ca++-binding in either protein. The data indicate that for both proteins the carbonyl group of the formylated N-terminal Met-1 and probably the carboxyl group of the subunit III (or c) C-terminal provide some of seven essential oxygen ligands normally required for defining a Ca++-binding site in proteins. Based on the accepted models for the hairpin conformation of the subunit III (c), it seems clear that the Ca++-binding site can form on the lumenal side of the membrane in the functional CF0 structures or on the periplasmic side of theE. coli membrane. A working hypothesis we are testing is that Ca++-binding to the CF0 (or F0) can form an easily reversible gating site such as to enhance the probability for membrane-localized H+ gradients being coupled to ATP formation under moderate energization loads, but under excess energization the local H+ ion concentration may build up high enough to displace the bound Ca++, resulting in delocalization of the H+ gradient. The latter situation seems, in chloroplasts at least, to function as a signal for over-energization; i.e., excess light absorption, a potential stress situation for plants. Lumenal acidification appears to be a trigger for initiating stress alleviation responses.On leave from the Institute of Soil Science and Photosynthesis, Russian Academy of Sciences, Puschchino, Russia. 相似文献
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An analysis of literary data concerning the physico-chemical properties of the hydrophobic fragment of bacterial, mitochondrial and chloroplast ATP-synthases has been carried out. The distribution patterns of enzyme subunits and of the whole enzyme complex are reviewed on the basis of amino acid analysis data taking account of physico-chemical characteristics of constituent amino acids. The roles of subunits, their invariant and other amino acids in the hydrophobic fragment function are discussed. 相似文献
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PHA-stimulated human lymphocytes (normal-resting-proliferating) at 0, 24, 48, 72, and 144 h were studied with Acridine Orange (AO) staining. By viable cell sorting, by subsequent subculturing, and by the use of biochemical, biophysical, and immunological assays, not only have the G0 resting and G1 (cycling) cell cycle phases been objectively characterized, but a separate subpopulation of quiescent cells that are functionally viable and deeply committed to nonproliferation, the Q cells, has been identified. Multiparameter cytofluorimetric analysis, methyl14C-thymidine incorporation, automated image analysis, and mitogen stimulation studies have shown that the "Q" cell, compared to the "G0" resting but easily recruitable cell, exhibits quite lower red and green AO emission, possesses 2c to 4c DNA content (rather than only 2c), has a higher average optical density, and is either nonrecruitable or recruitable-with-difficulty in PHA-stimulated lymphocyte cultures. 相似文献
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Tracy Smith Keith Pitts Jeffery A. McGarvey Anne O. Summers 《Applied microbiology》1998,64(4):1328-1332
We used metalloregulated luciferase reporter fusions and spectroscopic quantification of soluble Hg(II) to determine that the hydroperoxidase-catalase, KatG, of Escherichia coli can oxidize monatomic elemental mercury vapor, Hg(0), to the water-soluble, ionic form, Hg(II). A strain with a mutation in katG and a strain overproducing KatG were used to demonstrate that the amount of Hg(II) formed is proportional to the catalase activity. Hg(0) oxidation was much decreased in stationary-phase cells of a strain lacking KatG, suggesting that the monofunctional hydroperoxidase KatE is less effective at this reaction. Unexpectedly, Hg(0) oxidation also occurred in a strain lacking both KatE and KatG, suggesting that activities other than hydroperoxidases may carry out this reaction. Two typical soil bacteria, Bacillus and Streptomyces, also oxidize Hg(0) to Hg(II). These observations establish for the first time that bacteria can contribute, as do mammals and plants, to the oxidative phase of the global Hg cycle. 相似文献
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Corrado Di Nicola Claudio Pettinari Brian W. Skelton Allan H. White 《Inorganica chimica acta》2005,358(3):695-706
Single crystal X-ray structural characterizations are recorded for an array of adducts of the form AgX:dppf (1:1)(n), X = simple (pseudo-)halide or oxy-anion, ‘dppf’ = bis(diphenyl phosphino)ferrocene, for adducts X = Cl (new phase), Br, I, SCN, OCN, CN, NO3 (new phase), O2CCH3, n = 2, the form being dimeric [(dppf-P,P′)Ag(μ-X)2Ag(P,P′-dppf)], for X = I, SCN, [Ag(μ-X)2(P-dppf-P′)2Ag′]; for X = O2CCF3, n = ∞, the form is an extended polymer: ?Ag(O · CO · CF3)(P-dppf-P′)Ag′(O?. A dichloromethane solvate phase of CuI:dppf (1:1)2 (also centrosymmetric) is also recorded. Synthetic procedures for all adducts have been reported. All compounds have been characterized both in solution (1H, 13C, 31P NMR, ESI MS) and in the solid state (IR). The topology of the structures in the solid state was found to depend on the nature of the counterion. 相似文献
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Corrado Di Nicola Claudio Pettinari Brian W. Skelton Allan H. White 《Inorganica chimica acta》2006,359(1):53-63
Single crystal X-ray studies have defined the structures of a number of adducts of the form MX:dpex (2:1), M = univalent coinage metal (Cu, Ag), X = (pseudo-)halide, dpex = bis(diphenylpnicogeno)alkane, Ph2E(CH2)xEPh2, E = P, As, of diverse types, some novel. The adducts of AgCl,Br:dppm and AgNCO:dpem (x = 1) are tetranuclear as is the AgNO3:dppp (x = 3) array, all derivative of the familiar ‘step’ structure while the combination CuCN:dppm yields a two-dimensional web of twenty-membered macro/metallacycles. Synthetic procedures for all adducts have been reported. All compounds have been characterized both in solution (1H, 13C, 31P NMR, ESI MS) and in the solid state (IR). 相似文献
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