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101.
E. Cortes Toro J. J. M. De Goeij J. Bacso Yuan-Di Cheng L. Kinova J. Matsubara S. Niese T. Sato G. R. Wesenberg Y. Muramatsu R. M. Parr 《Journal of Radioanalytical and Nuclear Chemistry》1993,167(2):413-421
During a five-year period, the International Atomic Energy Agency supported a Coordinated Research Programme (CRP) to investigate the quantitative relationship between internal body burdens of a number of elements of environmental health significance and their respective concentrations in hair. The use of nuclear-related analytical techniques, such as neutron activation analysis, X-ray fluorescence, particle-induced X-ray emission and radiotracers, was emphasized. One aspect of the CRP focused on studies in man, using autopsy cases, of mineral distribution in five tissues, i.e. liver, kidney, lung, brain and bone in addition to hair, and the elements of primary importance were As, Cd, Cu, Hg, Pb, Se and Zn. Emphasis was placed on analytical quality assurance. Hair and internal tissue samples were obtained from subjects from Bulgaria, China, the former German Democratic Republic, Hungary, Japan, Norway and Sweden. 相似文献
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A gene encoding β-1,3-1,4-glucanase was cloned by polymerase chain reaction (PCR) from Bacillus subtilis MA139. Sequencing result showed 97% homology to the corresponding gene from Bacillus licheniformis. The open reading frame (ORF) of the gene contained 690 bp coding for a 226 amino-acid matured protein with the estimated
molecular weight of 24.44 kDa. The β-1,3-1,4-glucanase gene was subcloned into an expression vector of pET28a and expressed
in Escherichia coli BL21 and then purified by metal affinity chromatography using a nickel–nitrilotriacetic acid (Ni–NTA) column. The purified
β-1,3-1,4-glucanase demonstrated 24.05 and 12.52 U ml-1 activities for the substrates of barley β-glucan and lichenan, respectively, and the specific activities were 728.79 and
379.1 U mg-1 for them, respectively. The optimal temperature and pH of the purified enzyme were 40°C and 6.4, respectively. When barley
β-glucan was used as the substrate, K
m was 5.34 mg ml-1, and K
cat showed 7,206.71 S-1, thus the ratio of K
cat and K
m was 1,349.67 ml s-1 mg-1. The activity of β-1,3-1,4-glucanase was affected by a range of metal ions or ethylenediaminetetraacetic acid (EDTA). 相似文献
107.
Oka T Ito K Muramatsu M Ohdaira T Suzuki R Kobayashi Y 《The journal of physical chemistry. B》2006,110(41):20172-20176
Nanoporous polysiloxane films were fabricated by plasma polymerization of hexamethyldisiloxane mixed with cyclohexane under different conditions. The pores were generated through the elimination of carbonaceous aggregates (porogen) by annealing at 600 degrees C. Results of spectroscopic ellipsometry, Fourier transform infrared spectroscopy, and positron annihilation lifetime spectroscopy suggest that not only film porosity but also average pore size depends on the amount of the decomposable porogen. The pore size was controllable in a range between 0.6 and 1.0 nm in radius by proper selection of the substrate temperature and precursor composition. 相似文献
108.
Emission ratiometric imaging of intracellular zinc: design of a benzoxazole fluorescent sensor and its application in two-photon microscopy 总被引:7,自引:0,他引:7
Zinc and calcium are ubiquitous intracellular metals, and while a variety of quantitative probes have been developed for measuring intracellular changes in calcium concentration, the same is not true of zinc. We describe here the design, synthesis, and properties of the benzoxazole-based, ratiometric zinc probe, Zinbo-5. This bright fluorescent reporter has a quantum yield of 0.1 in the zinc-form, exhibits a Kd for Zn2+ in the nanomolar range, and shows significant changes in both excitation and emission maxima upon zinc binding. The utility of this cell permeable probe is demonstrated in fluorescence microscopy emission ratio imaging experiments on mammalian cells. We further show that Zinbo-5 is well suited for two-photon excitation microscopy ratio imaging and can readily reveal changes in intracellular zinc concentration within optical planes of single cells. To the best of our knowledge, this is the first example of two-photon excitation microscopy applied to ratio imaging of zinc. These methods can be applied to real-time emission or excitation ratio imaging studies of zinc physiology in living cells. 相似文献
109.
A cholesterol-conjugated fluorescence Zn(2+) sensor based on the fluorescein platform was designed and synthesized. The cholesterol moiety is essential for localizing the Zn(2+) sensor to the cell membrane, allowing the sensor to probe changes in the Zn(2+) concentration in a localized area of the cell. 相似文献