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排序方式: 共有216条查询结果,搜索用时 15 毫秒
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Song SH Dick B Zirak P Penzkofer A Schiereis T Hegemann P 《Journal of photochemistry and photobiology. B, Biology》2005,81(1):55-65
An absorption and emission spectroscopic characterisation of the combined wild-type LOV1-LOV2 domain string (abbreviated LOV1/2) of phot from the green alga Chlamydomonas reinhardtii is carried out at pH 8. A LOV1/2-MBP fusion protein (MBP=maltose binding protein) and LOV1/2 with a His-tag at the C-terminus (LOV1/2-His) expressed in an Escherichia coli strain are investigated. Blue-light photo-excitation generates a non-fluorescent intermediate photoproduct (flavin-C(4a)-cysteinyl adduct with absorption peak at 390 nm). The photo-cycle dynamics is studied by dark-state absorption and fluorescence measurement, by following the temporal absorption and emission changes under blue and violet light exposure, and by measuring the temporal absorption and fluorescence recovery after light exposure. The fluorescence quantum yield, phi(F), of the dark adapted samples is phi(F)(LOV1/2-His) approximately 0.15 and phi(F)(LOV1/2-MBP) approximately 0.17. A bi-exponential absorption recovery after light exposure with a fast (in the several 10-s range) and a slow component (in the near 10-min range) are resolved. The quantum yield of photo-adduct formation, phi(Ad), is extracted from excitation intensity dependent absorption measurements. It decreases somewhat with rising excitation intensity. The behaviour of the combined wildtype LOV1-LOV2 double domains is compared with the behaviour of the separate LOV1 and LOV2 domains. 相似文献
5.
B. W. Wenclawiak Torsten Hees Corinna E. Z?ller Hans-Peter Kabus 《Fresenius' Journal of Analytical Chemistry》1997,358(4):471-474
An on-line system of supercritical fluid extraction (SFE) and high performance liquid chromatography (HPLC) via solid phase
extraction (SPE) is described for the determination of palladium and rhodium 2,2,6,6-tetramethyl-3,5-heptanedione-(thd) as
well as rhodium-acetylacetonate-(acac) and benzylacetonate-(bzac) chelates. The chelates were extracted with supercritical
CO2 from sand and humic acid, concentrated on SPE cartridges and analysed with HPLC. Two cartridge materials were tested and
compared to off-line trapping. The percentage of the breakthrough and cartridge retained material were measured in liquid
dichloromethane. The SFE conditions could be optimized to separate metal chelates during the extraction. The supercritical
fluid (SF) behaviour of different ligands on rhodium were investigated.
Received: 19 July 1996/Revised: 11 December 1996/Accepted: 14 December 1996 相似文献
6.
Dieter Seebach Laurent Schaeffer Franois Gessier Pascal Bindschdler Corinna Jger Delphine Josien Sascha Kopp Grald Lelais YogeshR. Mahajan Peter Micuch Radovan Sebesta BerndW. Schweizer 《Helvetica chimica acta》2003,86(6):1852-1861
Multigram amounts of suitably protected β2‐amino acids with 17 of the 20 proteinogenic side chains are prepared by diastereoselective reactions of Li, B, or Ti enolates of the corresponding 3‐acyl‐4‐isopropyl‐5,5‐diphenyloxazolidin‐2‐ones (acyl‐DIOZ; 1 ) with appropriate electrophiles (amidomethylation, hydroxyalkylation, (benzyloxycarbonyl)methylation) in yields of 55–90% and with diastereoselectivities of 80 to >97% (Scheme). The primary products 2 – 8 thus obtained are converted to protected β2‐amino acids by standard procedures (Table 1). Many of the DIOZ derivatives are highly crystalline compounds (31 X‐ray crystal structures in Table 2). The chiral auxiliary DIOZ, readily prepared in either enantiomeric form, is recovered with high yield. 相似文献
7.
Joseph Grobe Duc Le Van Franz Immel Marianne Hegemann Bernt Krebs Mechtild Lge 《无机化学与普通化学杂志》1996,622(1):24-34
Reactive E = C(pp)π-Systems. XLII [1]. Novel Coordination Compounds of 2-(Diisopropylamino)-1-phosphaethyne: [{η4-(iPr2NCP)2}Ni{η2-(iPr2NCP)}], [(Ph3P)2Pt{η2-(iPr2NCP)}], and [Co2(CO)6{η2-μ2-(iPr2NCP)}] 2-(Diisopropylamino)-phosphaethyne iPr2N? C?P ( 2 ) reacts with the Ni(0)-complexes [Ni(1,5-cyclooctadiene)2] and [Ni(CO)3(1-azabicyclo[2.2.2]octane)], respectively, to give the novel complex [{η4-(iPr2NCP)2}Ni{η2-(iPr2NCP)}] ( 5 ), with the 1,3-diphosphacyclobutadiene derivative and 2 (side-on) as π-ligands. The molecular structure of 5 determined by X-ray diffraction on single crystals proves the spin systems and rotational barriers deduced from NMR-data (1H, 13C-, 31P). The PC distances of the four-membered ring of 1.817(2) and 1.818(2) Å – as expected – are considerably longer than the PC bond of the η2-coordinated phosphaalkyne 2 [1.671(2) Å]. – In the reactions of 2 with [(Ph3P)2Pt(C2H4)] or [Co2(CO)8] the ligand properties of 2 resemble those of alkynes affording the complexes [(Ph3P)2Pt{η2-(iPr2NCP)}] ( 7 ) with side-on coordinated 2 and [Co2(CO)6{η2-μ2-(iPr2NCP)}] with 2 acting as a 4e donor bridge in quantitative yield. In attempts to prepare copper(I) complexes of the aminophosphaalkyne 2 by reaction with CuCl or CuI the only isolable product formed in reasonable amounts under the influence of air and moisture is the 1 λ3, 3 λ5-diphosphetene (iPr2N) ( 10 ) (isolated yield: ca. 20%). The crystal structure analysis of 10 indicates a strong structural relationship to the diamino-2-phosphaallyl cation [Me(iPr2N)]+ ( 12 ), the 1,3-diphosphacyclobutadiene ligand (iPr2NCP)2 in the binuclear complex [{η1, μ2-(iPr2NCP)2}Ni2(CO)6] ( 3a ) as well as to the heterocycles (dme)2LiOE2′ (E′ = S, 11a ; E′ = Se, 11b ) prepared by Becker et al. [11b, 35]. 相似文献
8.
Volker Seibert Corinna Prohl Ida Schoultz Edward Rhee Rebecca Lopez Kareem Abderazzaq Chunshui Zhou Dieter A Wolf 《BMC biochemistry》2002,3(1):22-15
Background
SCF ubiquitin ligases share the core subunits cullin 1, SKP1, and HRT1/RBX1/ROC1, which associate with different F-box proteins. F-box proteins bind substrates following their phosphorylation upon stimulation of various signaling pathways. Ubiquitin-mediated destruction of the fission yeast cyclin-dependent kinase inhibitor Rum1p depends on two heterooligomerizing F-box proteins, Pop1p and Pop2p. Both proteins interact with the cullin Pcu1p when overexpressed, but it is unknown whether this reflects their co-assembly into bona fide SCF complexes. 相似文献9.
Corinna Kerst Rabah Boukherroub William J. Leigh 《Journal of photochemistry and photobiology. A, Chemistry》1997,110(3):215-246
The far-UV (193 nm) laser flash photolysis of nitrogen-saturated isooctane solutions of 1,1-dimethylsiletane allows the direct detection of 1,1-dimethylsilene as a transient species, which (at low laser intensities) decays with pseudo-first-order kinetics (τ 10 μs) and exhibits a UV absorption spectrum with λmax 255 nm. Characteristic rapid quenching is observed for the silene with methanol (kMcOH = (4.9 ± 0.2) × 109 M−1 s−1), tert-butanol (kBuOH = (1.8 ± 0.1) × 109 M−1 s−1) and oxygen (kO2 = (2.0 ± 0.5) × 108 M−1 s−1). The Arrhenius activation parameters for the reaction with methanol have been determined to be Ea = −2.6 ± 0.6 kcal mol−1 and log A = 7.7 ± 0.3. 相似文献
10.
Karcher Wolfgang Roth Stefan Spodarev Evgeny Walk Corinna 《Statistical Inference for Stochastic Processes》2019,22(2):263-306
Statistical Inference for Stochastic Processes - Given a low frequency sample of an infinitely divisible moving average random field $$\{\int _{\mathbb {R}^d} f(x-t)\varLambda (dx); \ t \in \mathbb... 相似文献