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921.
Reduction of the concentration difference of proteins in biological liquids using a library of combinatorial ligands 总被引:4,自引:0,他引:4
Thulasiraman V Lin S Gheorghiu L Lathrop J Lomas L Hammond D Boschetti E 《Electrophoresis》2005,26(18):3561-3571
The discovery of polypeptides and proteins with relevance to a particular biological state is complicated by their vast number and concentration range in most biological mixtures. Depletion methodologies are frequently used to remove the most abundant species; however, this removal not only fails significantly to enrich trace proteins, it may also nonspecifically deplete them due to their interactions with the removed high-abundance proteins. Here we report a simple-to-use methodology that reduces the protein concentration range of a complex mixture like whole serum through the simultaneous dilution of high-abundance proteins and the concentration of low-abundance proteins. This methodology utilizes solid-phase ligand libraries of immense diversity, generated by "split, couple, recombine" combinatorial chemistry, that are used for affinity-based binding to the proteins of a given mixture. With a controlled sample-to-ligand ratio it is possible to modulate the relative concentration of proteins such that many peptides or proteins that are undetectable by classical analytical methods become easily accessible. The reduction in the dynamic range of unfractionated serum is specifically described along with treatment of other proteomes such as extracts from Escherichia coli, chicken egg white and cell culture supernatant. Mono- and bi-dimensional electrophoresis (1-DE and 2-DE respectively) and surface-enhanced laser desorption/ionization-mass spectrometry (SELDI-TOF-MS) technology demonstrate the reduction in protein concentration range. Combining this approach with additional fractionation methods further increased the number of detectable species. 相似文献
922.
Theresa Julia Zielinski Michael R. Peterson Imre G. Csizmadia Robert Rein 《Journal of computational chemistry》1982,3(1):62-68
Ab initio SCF molecular orbital calculations have been performed to ascertain the conformational preferences of protonated, neutral, and deprotonated amidine [HC(?NH)NH2], using the 3-21G split valence basis set. The states of eight stable species, eight transition states, and four higher-order saddle points have been determined by complete geometry optimization utilizing analytic energy gradient techniques. Protonation at the amidine ?NH is preferred over the –NH2 site by 37.1 kcal/mol. Neutral amidine has rotational barriers of 9.6 and 11.7 kcal/mol for the HN?CN cis and trans isomers, respectively, while all the stable HC(NH2)2+ and HC(NH)2? species possess torsional barriers larger than 23 kcal/mol. There is, however, essentially free C—N single-bond rotation in HC(?NH)NH3+, the calculated barriers being 0.7 and 1.8 kcal/mol for the cis and trans HN?CN isomers, respectively. 相似文献
923.
A method was developed and fully validated for the quantitation of prazepam and its major metabolites, oxazepam and nordiazepam, in human plasma. Sample pretreatment was achieved by solid-phase extraction using Oasis HLB cartridges. The extracts were analysed by high-performance liquid chromatography (HPLC) coupled with single-quadrupole mass spectrometry (MS) with an electrospray ionization interface. The MS system was operated in the selected ion monitoring mode. HPLC was performed isocratically on a reversed-phase XTerra MS C18 analytical column (150 x 3.0 mm i.d., particle size 5 microm). Diazepam was used as the internal standard for quantitation. The assay was linear over a concentration range of 5.0-1000 ng ml(-1) for all compounds analyzed. The limit of quantitation was 5 ng ml(-1) for all compounds. Quality control samples (5, 10, 300 and 1000 ng ml(-1)) in five replicates from three different runs of analysis demonstrated an intra-assay precision (CV) of < or = 9.1%, an inter-assay precision of < or = 6.0% and an overall accuracy (relative error) of < 4.6%. The method can be used to quantify prazepam and its metabolites in human plasma covering a variety of pharmacokinetic or bioequivalence studies. 相似文献
924.
Dr. Ramadoss Govindarajan Shubham Deolka Dr. Eugene Khaskin Dr. Robert R. Fayzullin Dr. Shrinwantu Pal Dr. Serhii Vasylevskyi Prof. Julia R. Khusnutdinova 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(44):e202201639
We report a series of heterobimetallic Pt/Zn and Pt/Ca complexes to study the effect of proximity of a dicationic base metal on the organometallic Pt species. Varying degrees of Pt⋅⋅⋅Zn and Zn interaction with the bridging Me group are achieved, showcasing snapshots of a hypothetical process of retrotransmetalation from Pt to Zn. In contrast, only weak interactions were observed for Ca with a Pt-bound Me group. Activation of H2, B−H and Si−H bonds leads to the formation of hydride-bridged Pt−H−Zn complexes, which is not observed in the absence of Zn, pointing out the importance of metal-metal cooperation. Reactivity of PtMe2/M2+ with terminal acetylene, water and methanol is also studied, leading to facile protonation of one of the Me groups at the Pt center only when Zn is present. This study sheds light on various ways in which the presence of a 2+ metal cation significantly affects the reactivity of a common organoplatinum complex. 相似文献
925.
Mandi J. Curtis Julia Beaumont Fadil Elamin Andrew S. Wilson Hannah E. C. Koon 《Rapid communications in mass spectrometry : RCM》2022,36(13):e9305
Rationale
Sampling of dentine for stable carbon (δ13C) and nitrogen (δ15N) isotope ratios in the direction of tooth growth allows the study of temporal changes to the diet and physiological stress of an individual during tooth formation. Current methods of sampling permanent teeth using 1 mm increments provide temporal resolution of 6–9 months at best depending on the tooth chosen. Although this gives sufficient sample sizes for reliable analysis by mass spectrometry, sectioning the dentine across the incremental structures results in a rolling average of the isotope ratios. A novel method of incremental dentine collagen sampling has been developed to decrease the collagen increment size to 0.35 mm along the incremental structures, thus reducing averaging and improving the temporal resolution of short-term changes within the δ13C and δ15N values.Methods
This study presents data for a MicroMill-assisted sampling method that allows for sampling at 0.35 mm width × 1 mm depth increments following the incremental growth pattern of dentine. A NewWave MicroMill was used to sample the demineralised dentine section of modern donated human third molars from Sudan and compared to data from the same teeth using the 1 mm incremental sectioning method 2 established by Beaumont et al.Results
The δ13C and δ15N isotopic data showed an increased temporal resolution, with each increment providing data for 2–4 months of dentine formation.Conclusions
The data show the potential of this method for studying dietary reconstruction, nutritional stress, and physiological change with greater temporal resolution potentially to seasonal level and with less attenuation of the δ13C and δ15N values than was previously possible from human dentine.926.
Julia I. Nelina-Nemtseva Anna V. Gulevskaya Vitaliy V. Suslonov Alexander D. Misharev 《Tetrahedron》2018,74(10):1101-1109
π-Deficient ethynyl hetarenes were used as dipolarophiles in a 1,3-dipolar cycloaddition reaction with azomethine imines (2-arylidene-5-oxopyrazolidin-2-ium-1-ides). Both CuI-catalyzed and catalyst-free thermally induced reactions proceeded with high regioselectivity providing 6-hetaryl-5-aryl-2,3-dihydropyrazolo[1,2-a]pyrazol-1(5H)-ones in moderate to excellent yields. The ethynyl hetarenes (pyridines, pyrazines, quinoxalines, pteridines and pyrimido[4,5-c]pyridazines) with ortho-methyl, ortho-cyano and ortho-alkynyl substituents were applicable to this reaction. 1,3-Dipolar cycloaddition reactions of alkynyl hetarenes with azomethine imines or other 1,3-dipole reagents can be considered as an alternative synthetic approach to heterobiaryls. 相似文献
927.
Designed To React: Terminal Copper Nitrenes and Their Application in Catalytic C−H Aminations 下载免费PDF全文
Dr. Julian Moegling Dr. Alexander Hoffmann Fabian Thomas Nicole Orth Patricia Liebhäuser Dr. Ulrich Herber Robert Rampmaier Julia Stanek Dr. Gerhard Fink Prof. Dr. Ivana Ivanović‐Burmazović Prof. Dr. Sonja Herres‐Pawlis 《Angewandte Chemie (International ed. in English)》2018,57(29):9154-9159
Heteroscorpionate ligands of the bis(pyrazolyl)methane family have been applied in the stabilisation of terminal copper tosyl nitrenes. These species are highly active intermediates in the copper‐catalysed direct C?H amination and nitrene transfer. Novel perfluoroalkyl‐pyrazolyl‐ and pyridinyl‐containing ligands were synthesized to coordinate to a reactive copper nitrene centre. Four distinct copper tosyl nitrenes were prepared at low temperatures by the reaction with SO2tBuPhINTs and copper(I) acetonitrile complexes. Their stoichiometric reactivity has been elucidated regarding the imination of phosphines and the aziridination of styrenes. The formation and thermal decay of the copper nitrenes were investigated by UV/Vis spectroscopy of the highly coloured species. Additionally, the compounds were studied by cryo‐UHR‐ESI mass spectrometry and DFT calculations. In addition, a mild catalytic procedure has been developed where the copper nitrene precursors enable the C?H amination of cyclohexane and toluene and the aziridination of styrenes. 相似文献
928.
Structure,Physicochemical and Biological Properties of an Aqua (2,2′,2′′‐Nitrilotriacetato)‐oxidovanadium(IV) Salt with 4‐Methylpyridinium Cation 下载免费PDF全文
Aleksandra Tesmar Dariusz Wyrzykowski Katarzyna Kazimierczuk Julia Kłak Szymon Kowalski Iwona Inkielewicz‐Stępniak Joanna Drzeżdżon Dagmara Jacewicz Lech Chmurzyński 《无机化学与普通化学杂志》2017,643(7):501-510
The crystal structure of a nitrilotriacetate (nta) oxidovanadium(IV) salt with 4‐methylpyridinium cation, [4‐Me(Py)H]+, of [4‐Me(Py)H][VO(nta)(H2O)] stoichiometry was determined. The complex comprises a discrete mononuclear [VO(nta)(H2O)]– coordination entity that can be rarely found among other known compounds containing nitrilotriacetate oxidovanadium(IV) moieties. The complex was characterized by spectroscopic (IR and EPR) methods, magnetic measurements, and thermogravimetry (TG‐FTIR). The stability of the title compound in aqueous solutions was investigated by using the potentiometric titration method. Furthermore, spectrophotometric (UV/Vis) studies have revealed that the compound is capable to scavenge the superoxide free radicals (O2 ? –) as well as stable organic radicals i.e. 2,2′‐azinobis(3‐ethylbenzothiazoline‐6 sulfonic acid) cation radical (ABTS+ ? ) and 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH ? ). Finally, biological properties of the complex studied were investigated in relation to its cytoprotective activity against the oxidative damage generated exogenously by using hydrogen peroxide in the HT22 hippocampal neuronal cell line (the MTT assay). Additionally, the biological action of the compound towards two human osteosarcoma HOS and MG‐63 cell lines (the MTT and BrdU tests) as well as the untransformed human osteoblast hFOB 1.19 cell line was tested. 相似文献
929.
930.
It is proved that the integral is additive on simple summable functions of a generalized measure space. 相似文献