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排序方式: 共有250条查询结果,搜索用时 31 毫秒
21.
Natacha Lourette Heather Smallwood Si Wu Errol W. Robinson Thomas C. Squier Richard D. Smith Ljiljana Paša-Tolić 《Journal of the American Society for Mass Spectrometry》2010,21(6):930-939
A liquid chromatography-mass spectrometry (LC-MS)-based approach for characterizing the degree of nitration and oxidation of intact calmodulin (CaM) has been used to resolve ~250 CaM oxiforms using only 500 ng of protein. The analysis was based on high-resolution data of the intact CaM isoforms obtained by Fourier-transform ion cyclotron resonance mass spectrometry (FTICR MS) coupled with an on-line reversed-phase LC separation. Tentative identifications of post-translational modifications (PTMs), such as oxidation or nitration, have been assigned by matching observed protein mass to a database containing all theoretically predicted oxidation products of CaM and verified through a combination of tryptic peptide information (generated from bottom-up analyses) and on-line collisionally induced dissociation (CID) tandem mass spectrometry (MS/MS) at the intact protein level. The reduction in abundance and diversity of oxidatively modified CaM (i.e., nitrated tyrosines and oxidized methionines) induced by macrophage activation has been explored and semiquantified for different oxidation degrees (i.e., no oxidation, moderate, and high oxidation). This work demonstrates the power of the top-down approach to identify and quantify hundreds of combinations of PTMs for single protein target such as CaM and implicate competing repair and peptidase activities to modulate cellular metabolism in response to oxidative stress. 相似文献
22.
Jovica Stojanovi Tamara ?or?evi Ljiljana Karanovi 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(5):i55-i57
The structure of the title compound, ammineaquadi‐μ5‐phosphato‐trizinc(II), [Zn3(PO4)2(H2O)0.8(NH3)1.2], consists of two parts: (i) PO4 and ZnO4 vertex‐sharing tetrahedra arranged in layers parallel to (100) and (ii) ZnO2(N/O)2 tetrahedra located between the layers. Elemental analysis establishes the ammine‐to‐water ratio as 3:2. ZnO2(N/O)2 tetrahedra are located at special position 4e (site symmetry 2) in C2/c. The two O atoms of ZnO2(N/O)2 are bonded to neighbouring P atoms, forming two Zn—O—P linkages and connecting ZnO2(N/O)2 tetrahedra with two adjacent bc plane layers. A noteworthy feature of the structure is the presence of NH3 and H2O at the same crystallographic position and, consequently, qualitative changes in the pattern of hydrogen bonding and weaker N/O—H...O electrostatic interactions, as compared to two closely related structures. 相似文献
23.
24.
Jiawang Zhou Ljiljana Stojanovi Andrey A. Berezin Tommaso Battisti Abigail Gill Benson M. Kariuki Davide Bonifazi Rachel Crespo-Otero Michael R. Wasielewski Yi-Lin Wu 《Chemical science》2021,12(2):767
Development of purely organic materials displaying room-temperature phosphorescence (RTP) will expand the toolbox of inorganic phosphors for imaging, sensing or display applications. While molecular solids were found to suppress non-radiative energy dissipation and make the RTP process kinetically favourable, such an effect should be enhanced by the presence of multivalent directional non-covalent interactions. Here we report phosphorescence of a series of fast triplet-forming tetraethyl naphthalene-1,4,5,8-tetracarboxylates. Various numbers of bromo substituents were introduced to modulate intermolecular halogen-bonding interactions. Bright RTP with quantum yields up to 20% was observed when the molecule is surrounded by a Br⋯O halogen-bonded network. Spectroscopic and computational analyses revealed that judicious heavy-atom positioning suppresses non-radiative relaxation and enhances intersystem crossing at the same time. The latter effect was found to be facilitated by the orbital angular momentum change, in addition to the conventional heavy-atom effect. Our results suggest the potential of multivalent non-covalent interactions for excited-state conformation and electronic control.The number and position of halogen substituents in purely organic π–π* chromophores critically affect the efficiency of phosphorescence. 相似文献
25.
Slavik Jablan Ljiljana Radović Radmila Sazdanović 《Journal of mathematical chemistry》2011,49(10):2250-2267
Virtual knot theory offers the possibility to consider knots and links embedded on different surfaces. This paper analyzes
nonplanarity of graphs obtained from Gauss codes of virtual knots and links and their potential applications in chemistry. 相似文献
26.
Lukas Stolzer Antonina Vigovskaya Prof. Christopher Barner‐Kowollik Dr. Ljiljana Fruk 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(41):14309-14313
A photochemical approach based on nitrile imine‐mediated tetrazole‐ene cycloaddition is introduced to functionalize gold nanorods with biomolecules. For this purpose, a bifunctional, photoreactive linker containing thioctic acid as the Au anchoring group and a tetrazole moiety for the light‐induced reaction with maleimide‐capped DNA was prepared. The tetrazole‐based reaction on the nanoparticles’ surface results in a fluorescent pyrazoline product allowing for the spectroscopic monitoring of the reaction. This first example of nitrile imine‐mediated tetrazole‐ene cycloaddition (NITEC)‐mediated biofunctionalization of Au nanorods paves the way for the attachment of sensitive biomolecules, such as antibodies and other proteins, under mild conditions and expands the toolbox for the tailoring of nanomaterials. 相似文献
27.
V. M. Marković Ž. Čupić A. Ivanović Lj. Kolar-Anić 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(13):2327-2335
Stoichiometric network analysis (SNA) represents a powerful mathematical tool for stability analysis of complex stoichiometric
networks. Recently, the important improvement of the method has been made, according to which instability relations can be
entirely expressed via reaction rates, instead of thus far used, in general case undefined, current rates. Such an improved
SNA methodology was applied to the determination of exact instability conditions of the extended model of the hypothalamic-pituitary-adrenal
(HPA) axis, a neuroendocrinological system, whose hormone concentrations exert complex oscillatory evolution. For emergence
of oscillations, the Hopf bifurcation condition was utilized. Instability relations predicted by SNA showed good correlation
with numerical simulation data of the HPA axis model. 相似文献
28.
N. Pejić M. Vujković J. Maksimović A. Ivanović S. Anić Ž. Čupić Lj. Kolar-Anić 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(13):2310-2316
The non-periodic, periodic and chaotic regimes in the Bray-Liebhafsky (BL) oscillatory reaction observed in a continuously
fed well stirred tank reactor (CSTR) under isothermal conditions at various inflow concentrations of the sulfuric acid were
experimentally studied. In each series (at any fixed temperature), termination of oscillatory behavior via saddle loop infinite
period bifurcation (SNIPER) as well as some kind of the Andronov-Hopf bifurcation is presented. In addition, it was found
that an increase of temperature, in different series of experiments resulted in the shift of bifurcation point towards higher
values of sulfuric acid concentration. 相似文献
29.
Ivanović-Šašić AZ Marković VM Anić SR Kolar-Anić LjZ Cupić ŽD 《Physical chemistry chemical physics : PCCP》2011,13(45):20162-20171
By numerically simulating the Bray-Liebhafsky (BL) reaction (the hydrogen peroxide decomposition in the presence of hydrogen and iodate ions) in a continuously fed well stirred tank reactor (CSTR), we find "structured" types of chaos emerging in regular order with respect to flow rate as the control parameter. These chaotic "structures" appear between each two successive periodic states, and have forms and evolution resembling to the neighboring periodic dynamics. More precisely, in the transition from period-doubling route to chaos to the arising periodic mixture of different mixed-mode oscillations, we are able to recognize and qualitatively and quantitatively distinguish the sequence of "period-doubling" chaos and chaos consisted of mixed-mode oscillations (the "mixed-mode structured" chaos), both appearing in regular order between succeeding periodic states. Additionally, between these types of chaos, the chaos without such recognizable "structures" ("unstructured" chaos) is also distinguished. Furthermore, all transitions between two successive periodic states are realized through bifurcation of chaotic states. This scenario is a universal feature throughout the whole mixed-mode region, as well as throughout other mixed-mode regions obtained under different initial conditions. 相似文献
30.
Jelena Rogan Dejan Poleti Ljiljana Karanovi 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(7):m230-m233
The novel title coordination polymer, {[Cu(C8H4O4)(C10H9N3)]·H2O}n, synthesized by the slow‐diffusion method, takes the form of one‐dimensional zigzag chains built up of CuII cations linked by benzene‐1,3‐dicarboxylate (ipht) anions. An exceptional characteristic of this structure is that it belongs to a small group of metal–organic polymers where ipht is coordinated as a bridging tridentate ligand with monodentate and chelate coordination of individual carboxylate groups. The CuII cation has a highly distorted square‐pyramidal geometry formed by three O atoms from two ipht anions and two N atoms from a di‐2‐pyridylamine (dipya) ligand. The zigzag chains, which run along the b axis, further construct a three‐dimensional metal–organic framework via strong face‐to‐face π–π interactions and hydrogen bonds. A solvent water molecule is linked to the different carboxylate groups via hydrogen bonds. Thermogravimetric and differential scanning calorimetric analyses confirm the strong hydrogen bonding. 相似文献