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151.
Li D Zhu M Xu C Chen J Ji B 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(1):74-79
The interaction of rutin to bovine serum albumin (BSA) in aqueous solution was investigated by fluorescence spectra and ultraviolet-visible (UV-vis) spectra at pH 7.40. There are also some metal ions present in blood plasma, thus the research about the effect of metal ions on the interaction of drugs with proteins is crucial. Therefore, we have studied the effect of Cu2+ or Fe3+ on the interaction between rutin and BSA by using spectroscopic technique at pH 7.40, for the first time. The results of fluorescence titration indicated that rutin could quench the intrinsic fluorescence of BSA in a static quenching way. The binding sites number (n), the binding constant (K) and the spatial-distance (r) of rutin with BSA without or with Cu2+ or Fe3+ at 310 K were calculated. The result showed that the presence of Cu2+ or Fe3+ increased the binding constant and changed the binding distance between the acceptor and the donor, which possibly results from the formation of metal ions-BSA complex. The effect of rutin on the conformation of BSA was also analyzed using UV under experimental conditions. Furthermore, the fluorescence displacement experiments indicated that rutin is situated within subdomain IIA of BSA. 相似文献
152.
Dráb T Kračmerová J Tichá I Hanzlíková E Tichá M Liberda J 《Journal of separation science》2011,34(14):1692-1695
Native polyacrylamide electrophoresis in the presence of two reversible protein anionic stains (Ponceau S and Ponceau 2R) was used to study the oligomeric states of soluble proteins. A mild binding of the used protein stains to nondissociated protein oligomers imposed a charge shift on the proteins resulting into separation of protein species according to their size under physiological conditions. Adsorbed stains could be easily removed after electrophoresis by washing of polyacrylamide gel with buffer and protein complexes could be visualized either by the detection of their enzyme activity or by using a nonspecific protein stain. The specific detection of enzyme activity of glycosidases, lactate dehydrogenase, or phosphatases was shown as an example. 相似文献
153.
Ji D Wang L Hou S Liu W Wang J Wang Q Zhao ZK 《Journal of the American Chemical Society》2011,133(51):20857-20862
Many enzymes catalyzing biological redox chemistry depend on the omnipresent cofactor, nicotinamide adenine dinucleotide (NAD). NAD is also involved in various nonredox processes. It remains challenging to disconnect one particular NAD-dependent reaction from all others. Here we present a bioorthogonal system that catalyzes the oxidative decarboxylation of l-malate with a dedicated abiotic cofactor, nicotinamide flucytosine dinucleotide (NFCD). By screening the multisite saturated mutagenesis libraries of the NAD-dependent malic enzyme (ME), we identified the mutant ME-L310R/Q401C, which showed excellent activity with NFCD, yet marginal activity with NAD. We found that another synthetic cofactor, nicotinamide cytosine dinucleotide (NCD), also displayed similar activity with the ME mutants. Inspired by these observations, we mutated d-lactate dehydrogenase (DLDH) and malate dehydrogenase (MDH) to DLDH-V152R and MDH-L6R, respectively, and both mutants showed fully active with NFCD. When coupled with DLDH-V152R, ME-L310R/Q401C required only a catalytic amount of NFCD to convert l-malate. Our results opened the window to engineer bioorthogonal redox systems for a wide variety of applications in systems biology and synthetic biology. 相似文献
154.
Sonia Herranz Markéta Bocková María Dolores Marazuela Ji?í Homola María Cruz Moreno-Bondi 《Analytical and bioanalytical chemistry》2010,398(6):2625-2634
A surface plasmon resonance (SPR) biosensor for the detection of microcystins (MCs) in drinking water has been developed.
Several assay formats have been evaluated. The selected format is based on a competitive inhibition assay, in which microcystin-LR
(MCLR) has been covalently immobilized onto the surface of an SPR chip functionalized with a self-assembled monolayer. The
influence of several factors affecting sensor performance, such as the nature and concentration of the antibody, the composition
of the carrier buffer, and the blocking and regeneration solutions, has been evaluated. The optimized SPR biosensor provides
an IC50 0.67 ± 0.09 μg L−1, a detection limit of 73 ± 8 ng L−1, and a dynamic range from 0.2 to 2.0 μg L−1 for MCLR. Cross-reactivity to other related MCs, such as microcystin-RR (88%) and microcystin-YR (94%), has also been measured.
The SPR biosensor can perform four simultaneous determinations in 60 min, and each SPR chip can be reused for at least 40
assay–regeneration cycles without significant binding capacity loss. The biosensor has been successfully applied to the direct
analysis of MCLR in drinking water samples, below the provisional guideline value of 1 μg L−1 established by the World Health Organization for drinking water. 相似文献
155.
Jieni Li Henan Li Lai Liu Huizhen Yao Bingbing Tian Chenliang Su Haizhe Zhong Ye Wang Lifu Zhang Yumeng Shi 《化学:亚洲杂志》2019,14(16):2861-2868
Organometallic halide perovskites have attracted great research interest as light‐active materials for use in optoelectronics. Here, we report a high‐performance photoconductor based on a methylammonium lead iodide (MAPbI3) film that was prepared from a methylamine‐treated MAPbI3/PbI2 perovskite film. An ultrahigh responsivity of 3.6 A W?1 and detectivity of 5.4×1012 Jones were obtained for the film under 0.5 mW cm?2 white‐light illumination. In addition, under 420 nm light irradiation, the film exhibited its highest responsivity and detectivity of 30 A W?1 and 2.4×1014 Jones, respectively. The excellent photo‐response performance results from the improved electronic quality and suppressed nonradiative recombination channels of the treated perovskite thin film. 相似文献
156.
Shuangshuang Ji Xiuzhu Yang Xiaolong Chen Ang Li Doudou Yan Haiyan Xu Hao Fei 《Chemical science》2020,11(34):9126
The development of chemotherapy, an important cancer treatment modality, is hindered by the frequently found drug-resistance phenomenon. Meanwhile, researchers have been enthused lately by the synergistic use of chemotherapy with emerging immunotherapeutic treatments. In an effort to address both of the two unmet needs, reported herein is a study on a series of membrane active iridium(iii) complexed oligoarginine peptides with a new cell death mechanism capable of overcoming drug resistance as well as stimulating immunological responses. A systematic structure–activity relationship study elucidated the interdependent effects of three structural factors, i.e., hydrophobicity, topology and cationicity, on the regulation of the cytotoxicity of the Ir(iii)-oligoarginine peptides. With the most prominent toxicities, Ir-complexed octaarginines (R8) were found to display a progressive oncotic cell death featuring cell membrane-penetration and eruptive cytoplasmic content release. Consequently, this membrane-centric death mechanism showed promising potential in overcoming multiple chemical drug-resistance of cancer cells. More interestingly, the eruptive mode of cell death proved to be immunogenic by stimulating the dendritic cell maturation and inflammatory factor accumulation in mice tumours. Taking these mechanisms together, this work demonstrates that membrane active compounds may become the next generation chemotherapeutics because of their combined advantages.Structure optimized Ir-complexed cyclic octa-arginine shows a potential of “one-drug two-effects” for cancer treatment. 相似文献
157.
A series of new ligands L1-L7 were readily prepared in one step.Friedel-Crafts alkylation of indoles with nitroalkenes catalyzed by a novel Cu(Ⅱ)-L complex has been developed.The remarkable advantages of this reaction are mild reaction conditions,simple workup procedure,high yields of products and the use of ethanol as a green solvent. 相似文献
158.
Four novel fully π-conjugated α,ω-bis(terpyridine)oligothiophenes characterized by NMR, IR, and HR-mass spectroscopy are presented and their electronic absorption/emission and redox properties are described based on both experiments and theoretical calculations. These compounds can be potentially utilized as building blocks for preparation of conjugated metallo-supramolecular polymers or dynamers and related functional materials. 相似文献
159.
To investigate long-term CO2 behavior in geological formations and quantification of possible CO2 leaks, it is crucial to investigate the potential mobility of CO2 dissolved in brines over a wide range of spatial and temporal scales and density distributions in geological media. In this work, the mass transfer of aqueous CO 2 in brines has been investigated by means of a chemical potential gradient model based on non-equilibrium thermodynamics in which the statistical associating fluid theory equation of state was used to calculate the fugacity coefficient of CO2 in brine. The investigation shows that the interfacial concentration of aqueous CO2 and the corresponding density both increase with increasing pressure and decreasing temperature; the effective diffusion coefficients decrease initially and then increase with increasing pressure; and the density of the CO2 -disolved brines increases with decreasing CO2 pressure in the CO2 dissolution process. The aqueous CO2 concentration profiles obtained by the chemical potential gradient model are considerably different from those obtained by the concentration gradient model, which shows the importance of considering non-ideality, especially when the pressure is high. 相似文献
160.
Z. Y. Zhang B. Wu Y. H. Tang Z. X. Li Z. L. Sun L. Y. Chen Y. B. Ji C. H. Ma C. G. Huang 《Journal of Analytical Chemistry》2013,68(8):716-721
To characterize of the constituents in rat urine after oral administration of Radix Astragali decoction, a HPLC-DAD-MS/MS technique had been developed. Urine collected from 0 to 24 h, after administration, was purified using a C18 solid-phase extraction cartridge, and then detected by an on-line MS/MS detector. By comparing the retention times and MS/MS data with those obtained from authentic compounds and the published data, a total of 11 compounds including six flavonoids, one dipeptide, one triterpenoid and three of their metabolites in urine were identified. Compounds daidzein, genistein, quercetin, L-asparamide-D-phenylalanine, 4,2′,4′-trihydroxychalcone, Astragaloside-IV, daidzein sulfate, and kaempferol sulfate were for the first time detected by HPLC-MS/MS technique in urine. The present research results success-fully narrowed the range of effective constituents to be found in Astragalus membranaceus and would be useful for the following action mechanism research of this traditional Chinese medicine in treating various diseases. 相似文献