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11.
12.
A. K. Bakhshi P. Otto C.-M. Liegener E. Rehm J. Ladik 《International journal of quantum chemistry》1990,38(4):573-583
To model a real 20-component protein chain, the results of the electronic density of states (DOS ) of seven-component periodic and aperiodic polypeptide chains calculated on the basis of ab initio matrix block negative factor counting method are presented. The seven amino acid residues taken into account are rather different: glycine, serine, cysteine, asparagine, histidine, aspartic acid, and tryptophane. In the case of aperiodic chains, the energy states are found to be distributed over a much wider range of energy than in the corresponding periodic chains. In the intrinsic state, both periodic and aperiodic polypeptide chains are predicted to be insulators. The effect of the block copolymerization on the DOS distribution and the band gap values of both periodic and aperiodic polypeptide chains has been also investigated. Finally, the methods to calculate from the DOS curves hopping conductivities and the possibilities to compare them with experiment are outlined. 相似文献
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14.
An enzymatic assay for glucose based on the use of the fluorescent probe for hydrogen peroxide, europium(III) tetracycline (EuTc), is described. The weakly fluorescent EuTc and enzymatically generated H2O2 form a strongly fluorescent complex (EuTc–H2O2) whose fluorescence decay profile is significantly different. Since the decay time of EuTc–H2O2 is in the microseconds time domain, fluorescence can be detected in the time-resolved mode, thus enabling substantial reduction of background fluorescence. The scheme represents the first H2O2-based time-resolved fluorescence assay for glucose not requiring the presence of a peroxidase. The time-resolved assay (with a delay time of 60 s and using endpoint detection) enables glucose to be determined at levels as low as 2.2 mol L–1, with a dynamic range of 2.2–100 mol L–1. The method also was adapted to a kinetic assay in order to cover higher glucose levels (mmol L–1 range). The latter was validated by analyzing spiked serum samples and gave a good linear relationship for glucose levels from 2.5 to 55.5 mmol L–1. Noteworthy features of the assay include easy accessibility of the probe, large Stokes shift, a line-like fluorescence peaking at 616 nm, stability towards oxygen, a working pH of approximately 7, and its suitability for both kinetic and endpoint determination. 相似文献
15.
Otto M 《Fresenius' Journal of Analytical Chemistry》2001,369(7-8):738-740
The present situation of analytical chemistry teaching within a chemistry curriculum is exemplified by the reformed chemistry curriculum in Germany. This approach is contrasted with teaching analytical chemistry within a novel curriculum in natural sciences termed 'applied science'. The latter curriculum ensures a superior education in chemistry, physics, biology, mathematics and information science, thus gaining an integrated perspective of analytical chemistry. 相似文献
16.
Tatsuro Ouchi Hirotoshi Fujie Satoshi Jokei Yoshiomi Sakamoto Hidenori Chikashita Takeshi Inoi Otto Vogl 《Journal of polymer science. Part A, Polymer chemistry》1986,24(9):2059-2074
Acryloyl-type polymer fixing 1-β-carbonylethyl-5-fluorouracil residues through D -glucofuranoses via ester bonds was synthesized by means of polymerization of the corresponding monomer and polymer reaction. In order to provide the water-soluble objective polymer, the copolymerization of the acryloyl-type monomer with acrylamide was carried out. The extent of release of 5-FU residues from the copolymer was investigated in the enzyme or nonenzyme system in vitro. Furthermore, the antitumor activities of the water-insoluble homopolymer and water-soluble copolymer obtained were tested in vivo. 相似文献
17.
S. Steffen M. Otto L. Niewoehner M. Barth Z. Bro¿żek-Mucha J. Biegstraaten R. Horváth 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007
A gunshot residue sample that was collected from an object or a suspected person is automatically searched for gunshot residue relevant particles. Particle data (such as size, morphology, position on the sample for manual relocation, etc.) as well as the corresponding X-ray spectra and images are stored. According to these data, particles are classified by the analysis-software into different groups: ‘gunshot residue characteristic’, ‘consistent with gunshot residue’ and environmental particles, respectively. Potential gunshot residue particles are manually checked and – if necessary – confirmed by the operating forensic scientist. 相似文献
18.
Bassam Abu Thaher Jalal A. Zahra Mustafa M. El-Abadelah Hans-Hartwig Otto 《Monatshefte für Chemie / Chemical Monthly》2004,40(9):435-439
Nitrilimines were prepared from N-arylhydrazono chlorides and reacted with -alanine yielding the corresponding amidrazones, which were treated with 1,1-carbonyldiimidazole in THF affording the hitherto unknown 3-acetyl-1-aryl-1,4,5,6-tetrahydro-1,2,4-triazepin-7-ones. 相似文献
19.
van Wijk AA Spaans A Uzunbajakava N Otto C de Groot HJ Lugtenburg J Buda F 《Journal of the American Chemical Society》2005,127(5):1438-1445
To resolve the molecular basis of the coloration mechanism of alpha-crustacyanin, we used (13)C-labeled astaxanthins as chromophores for solid-state (13)C NMR and resonance Raman spectroscopy of [6,6',7,7']-(13)C(4) alpha-crustacyanin and [8,8',9,9',10,10',11,11',20,20']-(13)C(10) alpha-crustacyanin. We complement the experimental data with time-dependent density functional theory calculations on several models based on the structural information available for beta-crustacyanin. The data rule out major changes and strong polarization effects in the ground-state electron density of astaxanthin upon binding to the protein. Conformational changes in the chromophore and hydrogen-bond interactions between the astaxanthin and the protein can account only for about one-third of the total bathochromic shift in alpha-crustacyanin. The exciton coupling due to the proximity of two astaxanthin chromophores is found to be large, suggesting that aggregation effects in the protein represent the primary source of the color change. 相似文献
20.
Zusammenfassung Die Infrarot-und Raman-Spektren folgender Hydroxylamin-Derivate wurden registriert und zugeordnet: (CH3)3SiONH2 (1), (CH3)3SiONHSi(CH3)3, (CH3)3SiON[Si(CH3)3]2 (3), CH3ONH2 (4), CH3ON[Si(CH3)3]2 (5), CH3NHOCH3, CH3N[Si(CH3)3]OCH3, (C2H5)2NOH und (C2H5)2NOSi(CH3)3. Eine Normalkoordinatenanalyse für NH2OH,1, 3, 4 und5 zeigt, daß sich die Spektren durch Übertragung gleichbleibender Kraftkonstanten der Molekülfragmente wiedergeben lassen. O-und N-Substituenten beeinflussen die NO-Kraftkonstante nicht; die SiO-und SiN-Valenzkraftkonstanten sind mit 3,3 mdyn/Å bemerkenswert niedrig.
Mit 4 Abbildungen 相似文献
Vibrational spectra and normal coordinate analysis of some methyl-and trimethylsilylhydroxylamines
The infrared and Raman spectra of the hydroxylamine derivatives quoted above were recorded and frequencies assigned. A normal coordinate treatment of NH2OH,1, 3, 4 and5 showed that the spectra can be explained by a single force field set up by transferring force constants from the different fragments of the molecules. The NO stretching force constant remains unaffected by different substituents. The SiO and SiN stretching force constants are remarkably small (c. 3.3 mdyn/Å).
Mit 4 Abbildungen 相似文献