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1.
Vitally Sineshchekov Tilman Lamparter Elmar Hartmann 《Photochemistry and photobiology》1994,60(5):516-520
Abstract Comparative fluorescence and photochemical studies of phytochrome in etiolated seedlings of maize and in soluble and membrane-containing fractions isolated from them were camed out. The membrane fractions prepared in the absence of Mg2+ from etiolated coleoptiles contained 13% of total photoreversible phytochrome, which was readily solubilized by mild detergents. Its molecular size was indistinguishable from soluble phytochrome and equal to nondegraded maize phytochrome. Low-temperature fluorescence studies with intact tissue found that the position of the emission maximum at 85 K (λmax) and the extent of the phototransformation of the red-absorbing form (Pr) into the first stable photoproduct, lumi-R, at 85 K (γ1), varied in different parts of etiolated seedlings: λmax and γ1 reached their maximum values in the tips of coleoptiles and roots, 686 nm and 0.30–0.40, whereas the lowest values, 682 nm and ca 0.05, were observed in the root base. These parameters correlated well with those obtained for the pigment in the soluble and membrane-containing fractions: 684 and 680 nm, and 0.33 and 0.06, respectively. The extent of the Pr phototransformation into the far red-absorbing form (Pfr) (γ2) did not differ much: values of 0.80–0.85 and 0.70–0.75 correlated with the high and low values of γ1. These variations of the parameters were interpreted in agreement with our previous observations in terms of two phytochrome A species whose relative concentrations vary depending on the experimental conditions—the longer wavelength bulk light-labile species with high γ1 (Pr″), and the shorter wavelength minor light-stable species with low γ1 (Pr″). Close similarity between Pr’and the soluble phytochrome and between Pr″ and the membrane-bound phytochrome points to the possible origin of the native Pr’and PrPrime; species, thus providing evidence for the existence of membrane-bound pigment in the cell. 相似文献
2.
K. Dippel U. Klingebiel T. Kottke F. Pauer G. M. Sheldrick D. Stalke 《无机化学与普通化学杂志》1990,584(1):87-104
Fluorosilyl and Fluoroboryl Substituted Cyclotetrasilazanes. Synthesis and Crystal Structures Mono- and dilithiated octamethylcyclotetrasilazanes ( 1, 6 ) react with fluorosilanes and F2BN(SiMe3)2, respectively, under retention of the cyclotetrasilazane structure yielding the mono- and disubstituted compounds 2–5 and 7–13 . In the reaction of the dilithium compound 6 with a fluorsilane in equivalent amounts, the bicyclic compounds 14 and 15 are obtained. Crystallographic investigations of the compounds 2, 3, 8 , and 9 indicate that the monosilylated eight-membered ring has a cradle conformation while the disilylated ring has a chair conformation. The X-ray structure of the bicyclic system 14 indicates that the nitrogen atoms of the Si3N-units have a pyramidal environment. 相似文献
3.
In filaments of the moss Ceratodon purpureus , phototropism is controlled by the photoreceptor phytochrome. Thirty-three aphototropic mutants with a proposed defect in phytochrome-chromophore biosynthesis were isolated and analyzed. The phototropic response of those mutants was rescued with the precursor of the phytochrome chromophore, biliverdin. Phytochrome spectral activity was measured in 19 arbitrarily chosen mutants. All contained low but still measurable quantities of photoactive phytochrome; the highest level was around 15% of the wild-type. The level of total phytochrome (apophytochrome and holophytochrome) as assayed by immunoblotting was indistinguishable from wild-type. The content of photoactive phytochrome in Ceratodon is light-regulated. Phytochrome of wild-type kept for 24 h in red light was reduced to 50% as compared to dark controls but was unaffected by blue. The red-light-induced decrease was partially reversible by far-red light, indicating that phytochrome itself is the photoreceptor for this response. This regulation was further analyzed with the mutant ptr114 , which contains 15% photoactive phytochrome as compared to the wild-type. In this mutant, continuous red light given for 6 days decreased the level of spectrally active phytochrome down to 25% of dark controls, whereas the amount of phytochrome found on immunoblots was hardly reduced. This indicates that the loss of phytochrome affects only the holoprotein and implies that Ceratodon phytochrome is specifically degraded as a far-red-absorbing phytochrome. 相似文献
4.
Andreas Rahm Evgeni M. Kaidashev Heidemarie Schmidt Mariana Diaconu Andreas Pöppl Rolf Böttcher Christoph Meinecke Tilman Butz Michael Lorenz Marius Grundmann 《Mikrochimica acta》2006,153(1-2):21-25
A flow injection chemiluminescence method is proposed for the determination of cobalt, based on the strong catalytic effect
of Cobalt(II) (1,10-phenanthroline)3 complex on the lucigenin-periodate reaction in alkaline medium. Under the optimum experimental conditions, the chemiluminescence
signal responded linearly to the concentration of cobalt(II) in the 1.0 × 10−9–3.0 × 10−7 g mL−1 range with a detection limit of 4.4 × 10−10 g mL−1 cobalt(II). The relative standard deviation for the determination of 5.0 × 10−8 g mL−1 of cobalt was 2.3% in eleven replicated measurements. The method was successfully applied to the determination of cobalt(II)
in pharmaceutical preparations. 相似文献
5.
Tilman Krauch Bernd Schweizer 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):207-209
Abstract Through a direct and selective deprotection of 1 (R=methyl) with boron tribromide substituted o-hydroxy-dithiophosphinic acid 1 was prepared under mild conditions in excellent yield. 相似文献
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A heuristic for quadratic Boolean programs is presented. Computational tests with quadratic assignment problems (QAP) showed that it finds very good suboptimal solutions in moderate time and behaves computationally stable. In the appendix a FORTRAN-program for QAP is listed which improves an earlier code published by Burkard and Derigs. 相似文献
9.
The CO oxidation using mixtures of oxygen and nitrogen monoxide has been studied under stationary conditions. The measured selectivities could not always be foreseen from the results obtained in the binary systems CO/O2 and CO/NO. At high temperatures the amount of NO reduced is directly proportional to its fraction in the oxidizing gas. At low temperatures, NO may be reduced with high selectivity even in the presence of high oxygen concentration. 相似文献
10.
We have studied interacting and noninteracting quantum degenerate Fermi gases in a three-dimensional optical lattice. We directly image the Fermi surface of the atoms in the lattice by turning off the optical lattice adiabatically. Because of the confining potential, gradual filling of the lattice transforms the system from a normal state into a band insulator. The dynamics of the transition from a band insulator to a normal state is studied, and the time scale is measured to be an order of magnitude larger than the tunneling time in the lattice. Using a Feshbach resonance, we increase the interaction between atoms in two different spin states and dynamically induce a coupling between the lowest energy bands. We observe a shift of this coupling with respect to the Feshbach resonance in free space which is anticipated for strongly confined atoms. 相似文献