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991.
A. M. Saletskii A. G. Mel’nikov A. B. Pravdin V. I. Kochubei G. V. Meln’ikov 《Journal of Applied Spectroscopy》2008,75(3):402-406
We have studied the interaction between polycyclic aromatic hydrocarbons (pyrene and anthracene) with human serum albumin
(HSA) and human blood plasma. We have shown that the increase in the fluorescence intensity and the decrease in the polarity
index of pyrene on going from an aqueous solution to a pH 7.4 buffer solution of HSA suggests that polycyclic aromatic hydrocarbons
are localized in the hydrophobic microphase of the proteins. The increase in the fluorescence intensity for anthracene and
pyrene, and also the decrease in the polarity index of pyrene on going from HSA to blood plasma is connected with the fact
that polycyclic aromatic hydrocarbons can bind both to plasma proteins and to plasma lipids. When sodium dodecyl sulfate (SDS)
is added to the blood plasma in a concentration greater than the critical micelle concentration, we observe an increase in
the fluorescence intensity and the polarity index of pyrene. We hypothesize that this is connected with localization of pyrene
near the interface between the hydrophobic and hydrophilic phases of the protein-SDS system. We have established that SDS
leads to a change in the structure of blood plasma proteins and promotes escape of polycyclic aromatic hydrocarbons from the
protein globules.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 3, pp. 379–382, May–June, 2008. 相似文献
992.
Jan Vícha Michal Maloň Petra Veselá Otakar Humpa Miroslav Strnad Radek Marek 《Magnetic resonance in chemistry : MRC》2010,48(4):318-322
The 1H and 13C NMR resonances of 16 purine glucosides were assigned by a combination of one‐ and two‐dimensional NMR experiments, including gs‐COSY, gs‐HSQC, and gs‐HMBC, in order to characterize the effect of substituent and the position of glucose unit on the NMR chemical shifts. In addition, 15N NMR chemical shifts for selected derivatives were investigated by using 1H? 15N chemical shift correlation techniques. To map the influence of sugar moiety on the directly bonded nitrogen atom, selected N9‐glucosides and their ribose analogs were compared. Characteristic long‐range 1H? 15N coupling constants, measured by using 1H? 15N gradient‐selected single‐quantum multiple bond correlation (GSQMBC), are also reported and discussed. All compounds investigated here belong to cytokinins, an important group of plant hormones. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
993.
Al-Haddad A 《Talanta》2003,59(4):845-848
A back-flushing procedure using porous graphitic carbon (PGC) HPLC columns has been used successfully for the cleanup of soil samples for the determination of benzo[a]pyrene in ppb levels by an ODS-fluorescence HPLC column. The procedure was tested on nine random soil samples taken from an industrial area of the Kingdom of Bahrain. The mean percent recovery from the PGC column was 96% and the average coefficient of variation for the whole method was 5.2%. 相似文献
994.
Gamal Giuglio-TonoloThierry Terme Maurice MédebiellePatrice Vanelle 《Tetrahedron letters》2003,44(34):6433-6435
A series of disubstituted diarylethanols was prepared in moderate to good yields by reaction of p-nitrobenzyl chloride (1) with various aromatic aldehydes (2-12) in presence of tetrakis(dimethylamino)ethylene (TDAE). 相似文献
995.
996.
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998.
3,5-Disubstituted isoxazolines and isoxazoles have been synthesized using 1,3-dipolar cycloaddition of ferrocene derivatives FcCH=CH2, FcCOCH=CH2 and FcCCH with aliphatic and aromatic carbonitrileTV-oxides.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 139–142, January, 1994. 相似文献
999.
Matthew Marlow 《Analytica chimica acta》2004,526(1):41-49
The extraction and pre-concentration of phenol, 2-naphthol, and several hydroxyl polycyclic aromatic hydrocarbon (PAH) metabolites were investigated, using liquid-liquid-liquid microextraction (LLLME). The PAH metabolites are a very important class of compounds, and they have not been investigated previously by LLLME. For several of the hydroxyl PAH metabolites, the enrichment factors were small when using LLLME with an alkaline acceptor phase. Changing the acceptor phase to 1-octanol, which gave a two-phase system, improved the enrichment factors significantly for several of the hydroxyl PAH metabolites. For example, the enrichment factor was improved by a factor of 68.5 for 3-hydroxybenzo[a]pyrene. Enrichment factors were investigated as a function of time and stirring rate. At about 55 min the enrichment factor reached a maximum for the two-phase system and at approximately 75 min for the three-phase microextraction system. However, a 30 min extraction time was used for most of the experiments. Also, fluorescence spectroscopy was used to determine the enrichment factors and the mass distribution of the solute between the phases. Fluorescence spectroscopy was very effective in determining the very small concentrations of the solute in the various phases. In addition, capillary electrophoresis and LLLME were combined to demonstrate the substantial enrichment of 2-naphthol by combining these two approaches. 相似文献
1000.
A kinetic and product study of the dichloroacetic acid catalyzed chlorination of 1-methylpyrrole with 3- and 4-substituted N-chlorobenzamides was carried out. Protonated N-chlorobenzamides served as carriers of CI+. A Hammett correlation was obtained with ρ=−0.68 (r=0.98, n=8). General acid catalysis was observed with α=0.48 (r=0.99 and n=7). The yields of 2-chlorination (84±0.7%) and 3-chlorination (2.6±0.4%) were essentially constant (constant intramolecular selectivity) as the substituent on the N-chlorobenzamide was varied. Observation of constant intramolecular selectivity indicated that two intermediates were formed during the acid catalyzed chlorination of 1-methylpyrrole with N-chlorobenzamides. The carrier method is applicable to all types of aromatic systems and limited only by the availability of suitable carrier molecules. 相似文献