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91.
92.
Oxidation of NADH by decavanadate, a polymeric form vanadate with a cage-like structure, in presence of rat liver microsomes followed a biphasic pattern. An initial slow phase involved a small rate of oxygen uptake and reduction of 3 of the 10 vanadium atoms. This was followed by a second rapid phase in which the rates of NADH oxidation and oxygen uptake increased several-fold with a stoichiometry of NADH: O2 of 11. The burst of NADH oxidation and oxygen uptake which occurs in phosphate, but not in Tris buffer, was prevented by SOD, catalase, histidine, EDTA, MnCl2 and CuSO4, but not by the hydroxyl radical quenchers, ethanol, methanol, formate and mannitol. The burst reaction is of a novel type that requires the polymeric structure of decavanadate for reduction of vanadium which, in presence of traces of H2O2, provides a reactive intermediate that promotes transfer of electrons from NADH to oxygen. 相似文献
93.
Studies were carried out on the incidence of sister-chromatid exchanges induced in Chinese hamster ovary cells by in vitro treatment with the polycyclic aromatic hydrocarbons 7-methylbenz[a]anthracene and benzo[a]pyrene and with related K-region and non-K-region dihydrodiols. Appreciable increases in the incidence of sister-chromatid exchanges were apparent in cells treated with non-K-region dihydrodiols: the most active compounds were 3,4-dihydro-3,4-dihydroxy-7-methylbenz[a]anthracene and 7,8-dihydro-7,8-dihydroxybenzo[a]pyrene and the effects were dose-dependent. The parent hydrocarbons and the related K-region dihydrodiols induced some sister-chromatid exchanges but they were considerably less active than these two non-K-region diols. The results suggest that this system may usefully be applied to studies aimed at determining which dihydrodiols are important in the metabolic activation of the carcinogenic polycyclic hydrocarbons. These and other results also infer that Chinese hamster ovary cells possess some intrinsic ability to metabolize such compounds in the absence of exogenous activation systems. 相似文献
94.
Natarajan A Moerke N Fan YH Chen H Christ WJ Wagner G Halperin JA 《Bioorganic & medicinal chemistry letters》2004,14(10):2657-2660
Binding of eIF4E to the cap structure (m(7)GpppN) plays a critical role in mRNA translation. To study the interaction between eIF4E and cap, and to identify small molecule inhibitors of their binding, we synthesized a fluorescent-labeled cap analogue and used it to develop a fluorescence-polarization assay. This preliminary communication describes the synthesis of a fluorescein labeled 7-methylguanosinemonophosphate, and its dose dependent binding to purified human eIF4E as demonstrated by the fluorescence polarization assay. 相似文献
95.
The Flory temperatures (theta) measured by turbidity experiments performed on gelatin solutions were found to be 12 +/- 0.3, 13 +/- 0.3, 14 +/- 0.3, 14.5 +/- 0.3, and 15 +/- 0.3 degrees C for salt concentrations 0.1, 0.075, 0.05, 0.025, and 0 M (NaCl), respectively. Estimated persistence length (l(p)) of this weakly charged polyelectrolyte could be deduced from the Benoit and Doty (J. Phys. Chem. 1953, 57, 958) relationship with the approximation that this biopolymer assumes a compact near-globular shape at Flory temperature, implying l(p) = 9(R(h))(2)/(5L(m)), where L(m) is the contour length and R(h) is the hydrodynamic radius. It was found that l(p) approximately 2.2 +/- 0.2 nm at room temperature (20 degrees C), invariant of salt concentration. The Flory expansion factor (alpha= R(h)(T)/R(h)(theta) = 1.5+/-0.2) was found to be almost constant. theta-Composition for this biopolymer was deduced from turbidimitric titration of aqueous gelatin solutions with the alcohols methanol, ethanol, 2-propanol, and tert-butyl alcohol. It appears that hydrophobic interactions play a crucial role in causing chain collapse at theta-temperature and composition. 相似文献
96.
Chatterjee A Bhavesh NS Panchal SC Hosur RV 《Biochemical and biophysical research communications》2002,293(1):427-432
A novel protocol, based on the HN(C)N experiment, has been developed for rapid assignment of backbone H(N) and (15)N resonances in ((15)N, (13)C) labeled proteins. The protocol exploits the directly observable (15)N and H(N) sequential correlations and the distinctive peak patterns in the different planes of the HN(C)N spectrum, depending upon the nature of the residues displaying the correlations. Glycines and prolines, which are responsible for the distinctive features, provide many check/start points for the sequential walks. These features enhance the speed of data analysis and render side chain assignments less crucial for the success of the assignments. The application of the protocol has been demonstrated with FK506 binding protein (FKBP, molecular mass 12 kDa). 相似文献
97.
Bednarek MA MacNeil T Tang R Kalyani RN Van der Ploeg LH Weinberg DH 《Biochemical and biophysical research communications》2001,286(3):641-645
alpha-Melanotropin (alphaMSH) and several of its derivatives are potent but not selective agonists at melanocortin receptors 3, 4, and 5 present in the brain (MC3-5R). To differentiate between the physiological role of hMC-4R (believed to be involved in regulation of energy balance) from those of melanocortin receptors 3 and 5, potent and receptor-specific agonists are needed. Therefore, the cyclic derivatives of alphaMSH of a general structure, cyclo(X-His-d-Phe-Arg-Trp-Y)-NH(2), where X is succinic acid or an omega-amino-carboxylic acid, and Y is an alpha,omega-di-amino-carboxylic acid or an omega-carboxy-alpha-amino acid, were prepared and tested in binding assays and in cAMP assays on CHO cells expressing hMC3-5R. Several of the 21-membered or larger lactams turned out to be potent and hMC-4R-selective agonists. For instance, cyclo(CO-CH(2)-CH(2)-CO-His-d-Phe-Arg-Trp-Dab)-NH(2) (Dab: 2,4-di-amino-butyric acid) was a potent agonist at hMC-4R (EC(50) = 4 nM) with 55-fold selectivity over hMC-3R and greater than 1000-fold selectivity over hMC-5R. Another potent and selective compound was cyclo(NH-CH(2)-CH(2)-CO-His-d-Phe-Arg-Trp-Glu)-NH(2): EC(50) about 1 nM at hMC-4R, with 90-fold selectivity over hMC-3R and greater than 2000-fold selectivity over hMC-5R. 相似文献
98.
Amarnath Chatterjee Margaret A. Johnson Pedro Serrano Bill Pedrini Kurt Wüthrich 《Biomolecular NMR assignments》2007,1(2):191-194
Sequence-specific NMR assignments of an internal domain of the protein nsp3, nsp3(513–651), which is a part of the SARS coronavirus
(SARS-CoV) replicase polyprotein, have been determined, using triple-resonance NMR experiments with the uniformly [13C,15N]-labeled protein. The complete assignments (>99%) provide the basis for the ongoing three-dimensional structure determination. 相似文献
99.
Amarnath Singh Ritul Kamal Mohana Krishna Reddy Mudiam Manoj Kumar Gupta Gubbala Naga Venkata Satyanarayana Vipin Bihari Nishi Shukla Altaf Hussain Khan Chandrasekharan Nair Kesavachandran 《PloS one》2016,11(2)
Indoor air quality and heat exposure have become an important occupational health and safety concern in several workplaces including kitchens of hotels. This study investigated the heat, particulate matter (PM), total volatile organic compounds (TVOCs) and polycyclic aromatic hydrocarbons (PAHs) emissions in indoor air of commercial kitchen and its association with kidney dysfunctions among kitchen workers. A cross sectional study was conducted on 94 kitchen workers employed at commercial kitchen in Lucknow city, North India. A questionnaire-based survey was conducted to collect the personal and occupational history of the kitchen workers. The urine analysis for specific gravity and microalbuminuria was conducted among the study subjects. Indoor air temperature, humidity, wet/ dry bulb temperature and humidex heat stress was monitored during cooking activities at the kitchen. Particulate matter (PM) for 1 and 2.5 microns were monitored in kitchen during working hours using Hazdust. PAHS in indoor air was analysed using UHPLC. Urinary hydroxy-PAHs in kitchen workers were measured using GC/MS-MS. Higher indoor air temperature, relative humidity, PM1 and PM2.5 (p<0.001) was observed in the kitchen due to cooking process. Indoor air PAHs identified are Napthalene, fluorine, acenaphthene, phenanthrene, pyrene, chrysene and indeno [1,2,3-cd) pyrene. Concentrations of all PAHs identified in kitchen were above the permissible OSHA norms for indoor air. Specific gravity of urine was significantly higher among the kitchen workers (p<0.001) as compared to the control group. Also, the prevalence of microalbuminuria was higher (p<0.001) among kitchen workers. Urinary PAH metabolites detected among kitchen workers were 1-NAP, 9-HF, 3-HF, 9-PHN and 1-OHP. Continuous heat exposure in kitchens due to cooking can alter kidney functions viz., high specific gravity of urine in kitchen workers. Exposure to PM, VOCs and PAHs in indoor air and presence of urinary PAHs metabolites may lead to inflammation, which can cause microalbuminuria in kitchen workers, as observed in the present study. 相似文献
100.
Arthur D. Broom Venkataraman Amarnath 《Biochemical and biophysical research communications》1976,70(4):1029-1034
The synthesis of poly(1-methyl-6-thioinosinic acid) and a comparison of its properties with those of poly(6-thioinosinic acid) and poly(6-methylthiopurinylic acid) are reported. In contrast to 6-thioinosine 5′-diphosphate, 1-methyl-6-thioinosine 5′-diphosphate was found to be a substrate for polynucleotide phosphorylase-catalyzed homopolyribonucleotide synthesis. Poly(1-methyl-6-thioinosinic acid) appears to form a single stranded helical array with a highly cooperative melting transition (Tm = 12°C) and a very large bathochromic shift (12 nm) in the absorption maximum upon melting. 相似文献