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Zeng T Jamshidi Z Mori H Miyoshi E Klobukowski M 《Journal of computational chemistry》2007,28(12):2027-2033
We carried out computational studies of OPX3 and SPX3 (X = Br and I) molecules and their corresponding anions using density functional theory, Møller‐Plesset, and CCSD(T) methods with newly developed model core potentials (MCP). Reliabilities of the MCP were demonstrated by comparing experimental and calculated results. We computed the geometric structure, electron affinities, and electrostatic moments using systematic sequences of the dzp‐, tzp‐, and qzp‐quality basis sets. Both C3v and Cs symmetries were assumed to ascertain that minima on the potential energy surface were found. Infrared and Raman frequencies were calculated and compared with available experimental data. Natural population analyses were performed and used to determine distribution of the extra electron in anions. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007 相似文献
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An attempt was made to quantitatively describe the binding of phenylarsenic species to thiol-containing biomolecules using electrospray ionization mass spectrometry (ESI-MS). The extent of the reactions of phenylarsine oxide (PAO) with the peptides glutathione and isotocin (ITC) and with the protein thioredoxin resulting in covalent As--S bonds were quantified by deriving the dependence of the corresponding ion signal intensities on the concentration of the reaction products. Problems complicating a quantitative evaluation of the mass spectra, such as signal suppression effects, were critically evaluated. Equilibrium constants for condensation reactions as well as formation constants for noncovalent associations were calculated by means of ESI-MS signal intensities. The comparison of the reaction of PAO with different thiol reactants revealed the highest binding affinity for ITC followed by thioredoxin and a lower affinity to glutathione. Possibly, the intramolecular formation of RS-As(C(6)H(5))-SR occurring in case of ITC and thioredoxin is favored over the intermolecular product involving two molecules glutathione even though the molecular mass of glutathione (307 g mol(-1)) is much smaller than that of ITC (966 g mol(-1)) and thioredoxin (11 688 g mol(-1)). A similar binding affinity for trivalent (K approximately 1.6 x 10(-3) l micromol(-1)) and pentavalent (K approximately 1.6 x 10(-3) and 1.0 x 10(-3) l micromol(-1)) arsenic species was found for the formation of a noncovalent complex of glutathione with different phenylarsenic compounds. 相似文献
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Desorption/ionization on porous silicon (DIOS) is a very useful technique in the case of small molecular weight compounds, compared to the matrix-assisted laser desorption ionization (MALDI). This is because MALDI generates matrix-related ions that overlap with the mass range of interest. The aim of our work was to investigate the suitability of the DIOS technique in the case of fatty acids in negative ion mode. The analysis of the chosen fatty acid models, nonadecanoic acid (C(19)H(38)O(2)) and heneicosanoic acid (C(21)H(42)O(2)), gave rise to the observation of the deprotonated monomeric species and selective cationized multimeric species. This cation selectivity was further elucidated by complementary studies based on the addition of various metals such as Ag(I), Zn(II), Fe(II), and also Cu(II). Specific behavior, depending upon the introduced metal, was highlighted by different redox reaction processes and also metastable decompositions (in PSD mode). 相似文献
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El-Khouly ME Kang ES Kay KY Choi CS Aaraki Y Ito O 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(10):2854-2863
Silicon-phthalocyanine-cored fullerodendrimers with up to eight fullerene substituents (SiPc-n C(60); n=2, 4, and 8) have been synthesized. Photophysical properties of newly synthesized SiPc-n C(60) have been investigated by time-resolved fluorescence and transient absorption analysis with pulsed laser light. Laser photolysis measurements suggest the occurrence of a charge-separation process from (1)SiPc* to the C(60) subunits. The nanosecond transient absorption spectra in the near-IR region indicate that the lifetimes of the formed radical ion pairs are prolonged on the order of SiPc-8 C(60)>SiPc-4 C(60)>SiPc-2 C(60), which may be related to the electron migration among the C(60) subunits. The usefulness of SiPc-n C(60) as light-harvesting systems, evaluated as a ratio of the rates of charge recombination to those of charge separation, increases markedly with the dendrimer generation. 相似文献
958.
Hapten heterology for a specific and sensitive indirect enzyme-linked immunosorbent assay for organophosphorus insecticide fenthion 总被引:1,自引:0,他引:1
Five haptens with different spacer-arm attachment sites on the structure of the organophosphorus insecticide fenthion were designed and synthesized. All of the haptens were conjugated with ovalbumin (OVA) for the coating antigen, and three haptens containing all or most of the structure of fenthion were conjugated with bovine serum albumin (BSA) for the immunogen. Six polyclonal antisera were raised against the three BSA conjugates, and 30 antibody/coating conjugate combinations were selected for studies of assay sensitivity and specificity for fenthion. The study revealed the best combination with high sensitivity (I50 of 0.08 ng mL−1) and high assay specificity, which indicated that when structural difference between the analyte and an immunizing hapten is less than that between a coating hapten and the immunizing hapten, a high sensitive enzyme-linked immunosorbent assay (ELISA) in the heterologous system may stand a good chance to be developed. The immunity results showed that heterology in the hapten spacer-arm attachment site of the immunogen could achieve a remarkable improvement in the quantity, sensitivity, and/or specificity of antibody, and that the moiety of an analyte, which is the same as the moiety near/on the immunizing spacer-arm hapten attachment site, contributes greatly to the interaction of antibody and hapten. 相似文献
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