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51.
52.
Preparative two-dimensional gel electrophoresis with agarose gels in the first dimension for high molecular mass proteins 总被引:5,自引:0,他引:5
A two-dimensional gel electrophoresis (2-DE) method that uses an agarose isoelectric focusing (IEF) gel in the first dimension (agarose 2-DE) was compared with an immobilized pH gradient 2-DE method (IPG-Dalt). The former method was shown to produce significant improvements in the 2-D electrophoretic separation of high molecular mass proteins larger than 150 kDa, up to 500 kDa, and to have a higher loading capacity, as much as 1.5 mg proteins in total for micropreparative runs. The extraction medium found best in this study for agarose 2-DE of mammal tissues was 6 M urea, 1 M thiourea, 0.5% 2-mercaptoethanol, protease inhibitor cocktail (Complete Mini EDTA-free), 1% Triton X-100 and 3% 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS). Trichloroacetic acid (TCA) treatment of the agarose gel after IEF is to be carefully weighed beforehand, because some high molecular mass proteins were less likely to enter the second-dimensional polyacrylamide gel after TCA fixation, and proteins such as mouse skeletal muscle actin gave pseudospots in the agarose 2-DE patterns without TCA fixation. As a good compromise we suggest fixation of proteins in the agarose gel with TCA for one hour or less. The first-dimensional agarose IEF gel containing Pharmalyte as a carrier ampholyte was 180 mm in length and 2.5-4.8 mm in diameter. The gel diameter was shown to determine the loading capacity of the agarose 2-DE, and 1.5 mg liver proteins in total were successfully separated by the use of a 4.8 mm diameter agarose gel. 相似文献
53.
Summary In the aqueous solutions of poly(N-vinylacetamide) in the presence of Na2SO4 or (NH4)2SO4, the intrinsic viscosities were small and the Huggins constants were large compared with those in water. Similar but much
less effects were observed for NaF. Opposite effects were found, however, for NaSCN. The poor solvent quality of aqueous sulfate
solutions was significantly improved by the addition of guanidine hydrochloride to 3 M or higher. Urea was much less effective
in improving the solvent quality. The different M28.8neffects observed between urea and GdnHCl may be explained by their different
binding affinities to amide group. Solubilization of PNVA flocculates induced by the presence of 0.8 M Na2SO4 took place by adding urea to 1 M, although only small changes were detected in the viscosity behavior accompanying the addition
of 1 M urea.
Received: 12 June 1997 Accepted: 4 August 1997 相似文献
54.
Maeda H 《Journal of colloid and interface science》2003,258(2):390-395
A simple analytical expression is presented to describe the dependence of the degree of counterion binding beta of ionic-nonionic mixed micelles on the composition x(I) (the micelle mole fraction of the ionic species): 1/(1-beta)=1-x(I)+x(I)/[1-beta(x(I)=1)]. In the application of the relation, the value of beta for the pure ionic micelle, beta(x(I)=1), should be known in advance. An equivalent expression was first proposed by Hall et al. on purely empirical grounds but in the present study the relation is derived on the basis of the Poisson-Boltzmann equation of the plate model of micelles in a salt-free medium. The insensitive nature of beta toward a change in micelle concentration as well as to the addition of a salt is also derived under reasonable approximations. When the relation was applied to 12 mixed micelles both with and without added salt, it described quite well the observed composition dependencies of all examples examined. Two other simple analytical expressions are also derived, but they are much less satisfactory in describing the experimental data. 相似文献
55.
Utilizing a commercially available helium-purging device and PEEK tubes for all tubing, especially for connection between the mobile phase and pump, high performance liquid chromatography with an electrochemical detector (ECD/HPLC) at the cathodic mode is a simple and precise method for the determination of p-nitrophenol (NP). Studies with cyclic and hydrodynamic voltammetry indicated that 25% aqueous MeOH containing 0.1% (v/v) CF(3)CO(2)H and -0.8 V vs. Ag/AgCl are the best mobile phase and detection potential for cathodic ECD/HPLC. With the present system, the limits of detection and determination were 0.2 and 0.25 microM, respectively, and up to 50 microM, a linear calibration curve was afforded. Within-day precisions for the analysis of 5 and 50 microM NP were 0.8 and 0.7% (n=6), respectively, and between-day precisions (n=6) for these samples were 3.5 and 2.2%, respectively. Compared with the commonly used Bessey-Lowry-Brock method, cathodic ECD/HPLC was useful for the assay of acid phosphatase in urine samples with p-nitrophenyl phosphate disodium salt as a substrate. 相似文献
56.
Kenji Maeda Ross A. Miller Ali Shafiee Joseph D. Armstrong III 《Tetrahedron letters》2005,46(9):1545-1549
Highly diastereoselective (>20:1) bromo-lactonization of N-sulfonyl-2-allyl-2-phenylglycine methyl ester (11) was observed. Successive treatment of the chiral lactone with MeONa gave the desired (2S,4R)-4-hydroxy-2-phenylproline derivative in high yield without erosion of the diastereoselectivity. The starting chiral non-racemic compound (5) was prepared from the racemic 2-phenylglycine using a classical kinetic resolution (crystallization), an asymmetric phase transfer alkylation, and an enzyme-catalyzed kinetic resolution. 相似文献
57.
Zhang X Furutachi H Fujinami S Nagatomo S Maeda Y Watanabe Y Kitagawa T Suzuki M 《Journal of the American Chemical Society》2005,127(3):826-827
(mu-Hydroxo or oxo)(mu-1,2-peroxo)diiron(III) complexes having a tetradentate tripodal ligand (L) containing a carboxylate sidearm [Fe2(mu-OH or mu-O)(mu-O2)(L)2]n+ were synthesized as models for peroxo-intermediates of non-heme diiron proteins and characterized by various physicochemical measurements including X-ray analysis, which provide fundamental structural and spectroscopic insights into the peroxodiiron(III) complexes. 相似文献
58.
Chan Sik Cho Tae Kyung Kim Bok Tae Kim Tae-Jeong Kim Sang Chul Shim 《Journal of organometallic chemistry》2002,650(1-2):65-68
Nitroarenes react with trialkylamines in the presence of a catalytic amount of a ruthenium catalyst together with tin(II) chloride dihydrate at 180 °C in an aqueous medium (toluene–H2O) to afford the corresponding quinolines in moderate to good yields. The catalytic pathway seems to be proceeded via a sequence involving initial reduction of nitroarenes to anilines, alkyl group transfer from alkylamines to anilines to form an imine, dimerization of imine, and heterocyclization. 相似文献
59.
Alfred Trautwein Yutaka Maeda Frank E. Harris Helmuth Formanek 《Theoretical chemistry accounts》1974,36(1):67-76
Experimental Mössbauer spectra of the Fe57-enriched CO complex of sperm whale myoglobin (MbCO) at T= 4.2 K with and without applied magnetic field (H⊥γ) were measured to derive the sign of the electric field gradient (EFG), the quadrupole splitting ΔE Q, and the isomer shift δ of the heme iron. We find a positive EFG, δE Q = 0.363 mm/sec, and δ + 0.266 mm/sec. Molecular orbital calculations were carried out to obtain theoretical estimates of EFG and ΔE Q for several steric arrangements of the CO ligand relative to the heme group. Our results are most consistent with the conclusion that the iron is situated in the heme plane, and that a bent geometry with a Fe-C-O angle of about 135 ° is more favorable than a more symmetric structure with a linear Fe-C-O geometry. 相似文献
60.
Takehiko Yamato Fumika Kitajima Jeong Tae Gil 《Journal of inclusion phenomena and macrocyclic chemistry》2005,53(3-4):257-262
The lower rim functionalized hexahomotrioxacalix[3]arene triamide 4 with cone-conformation was synthesized from triol 1 by a stepwise reaction. The different extractability for alkali metal ions, transition metal ions, and alkyl ammonium ions from water into dichloromethane is discussed. Due to the strong intramolecular hydrogen bonding between the neighboring NH and CO groups in triamide 4, its affinity to metal cations was weakened. Triamide 4 shows a single selectivity to n-BuNH 3 + . The anion complexation of triamide 4 was also studied by 1H NMR titration experiments. Triamide 4 binds halides through the intermolecular hydrogen bonding among the NH hydrogens of amide in a 1:1 fashion in CDCl3. The association constants calculated from these changes in chemical shifts of the amide protons are K a = 223 M?1 for Cl? and K a = 71.7 M?1 for Br?. Triamide 4 shows a preference for Cl? complexation than Br? complexation. 相似文献