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温度对铽(Ⅲ)-转铁蛋白溶液构象的影响 总被引:1,自引:0,他引:1
在pH 7.4,0.01 mol/L N-2-羟乙基哌嗪-N′-2-乙磺酸(Hepes)条件下,铽(Ⅲ)与N,N′-二(2-羟苄基)乙二胺-N,N′-二乙酸(HBED)结合并发生交换相互作用使铽(Ⅲ)荧光增强104倍,通过监测铽(Ⅲ)545 nm荧光强度的变化测定了Tb-HBED配合物的条件稳定常数是lgK=14.30±0.49;Tb-HBED配合物中配体、铽(Ⅲ)荧光强度均随着温度的升高而降低.在pH 7.4,0.01 mol/L Hepes条件下,TbN-apoTf-Tbc配合物中蛋白质的荧光强度随着温度的升高而降低,而能量受体铽(Ⅲ)的荧光强度随着温度的升高而增强,主要源于铽(Ⅲ)与螺旋5色氨酸残基间的无辐射能量转移;当温度由0℃上升到55℃时,平均能量转移效率AE值增加了29%,给体、受体间距离R有约4.2%的减小,温度变化引起TbN-apoTf-Tbc配合物大的构象变化;铽(Ⅲ)与人血清脱铁转铁蛋白的结合使蛋白质的变性温度降低.同样条件下,TbN-apoOTf-Tbc配合物与TbN-apoTf-Tbc配合物有所不同,虽然能量给体的荧光强度随着温度的增加而减小,但铽(Ⅲ)荧光强度没有明显的增强;铽(Ⅲ)对蛋白质的变性温度几乎没有影响. 相似文献
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温度对铽(III)-转铁蛋白溶液构象的影响 总被引:2,自引:0,他引:2
在pH 7.4,0.01 mol/L N-2-羟乙基哌嗪-N’-2-乙磺酸(Hepes)条件下,铽 (III)与N,N’-二(2-羟苄基)乙二胺-N,N’-二乙酸(HBED)结合并发生交换 相互作用使铽(III)荧光增强10~4倍,通过监测铽(III)545 nm荧光强度的变化 测定了Tb-HBED配合物的条件稳定常数是lgK = 14.30 ± 0.49;Tb-HBED配合物中 配体、铽(III)荧光强度均随着温度的升高而降低。在pH 7.4,0.01 mol/L Hepes条件下,Tb_N-apoTf-Tb_C配合物中蛋白质的荧光强度随着温度的升高而降 低,而能量受体铽(III)的荧光强度随着温度的升高而增强,主要源于铽(III) 与螺旋5色氨酸残基间的无辐射能量转移;当温度由0 ℃上升到55 ℃时,平均能量 转移效率AE值增加了29%,给体、受体间距离R有约4.2%的减小,温度变化引起 Tb_N-apoTf-Tb_C配合物大的构象变化;铽(III)与人血清脱铁转铁蛋白的结合使 蛋白质的变性温度降低。同样条件下,Tb_N-apoOTf-Tb_C配合物与Tb_N-apoTf- Tb_C配合物有所不同,虽然能量给体的荧光强度随着温度的增加而减小,但铽( III)荧光强度没有明显的增强;铽(III)对蛋白质的变性温度几乎没有影响。 相似文献
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在pH 7.4,0.01 mol/L N-2-羟乙基哌嗪-N’-2-乙磺酸(Hepes)条件下,铽 (III)与N,N’-二(2-羟苄基)乙二胺-N,N’-二乙酸(HBED)结合并发生交换 相互作用使铽(III)荧光增强10~4倍,通过监测铽(III)545 nm荧光强度的变化 测定了Tb-HBED配合物的条件稳定常数是lgK = 14.30 ± 0.49;Tb-HBED配合物中 配体、铽(III)荧光强度均随着温度的升高而降低。在pH 7.4,0.01 mol/L Hepes条件下,Tb_N-apoTf-Tb_C配合物中蛋白质的荧光强度随着温度的升高而降 低,而能量受体铽(III)的荧光强度随着温度的升高而增强,主要源于铽(III) 与螺旋5色氨酸残基间的无辐射能量转移;当温度由0 ℃上升到55 ℃时,平均能量 转移效率AE值增加了29%,给体、受体间距离R有约4.2%的减小,温度变化引起 Tb_N-apoTf-Tb_C配合物大的构象变化;铽(III)与人血清脱铁转铁蛋白的结合使 蛋白质的变性温度降低。同样条件下,Tb_N-apoOTf-Tb_C配合物与Tb_N-apoTf- Tb_C配合物有所不同,虽然能量给体的荧光强度随着温度的增加而减小,但铽( III)荧光强度没有明显的增强;铽(III)对蛋白质的变性温度几乎没有影响。 相似文献
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含铽三元共聚物的合成及其发光性能研究 总被引:4,自引:0,他引:4
报道了新型的可平衡电荷(空穴与电子)传输的稀土铽-聚合物发光材料的合成, 将稀土铽配合物单体与乙烯基咔唑、甲基丙烯酸甲酯共聚制得含咔唑和稀土铽配合物的HTL-EML-ETL三功能合一的聚合物, 通过FT-IR, GPC, NMR及元素分析对其结构进行表征, 并研究了这类材料的光致及电致发光性能. 在含铽三元共聚物的薄膜荧光中, 来自咔唑基的荧光出现“固态猝灭”, 而来自稀土铽离子的荧光则明显加强, 这是由于二者的失活机制不同引起的. 以含铽三元共聚物制作的单层器件主要发射铽离子的特征荧光. 相似文献
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激光-液体荧光法研究——Ⅰ.稀土元素铽、镝和钐的测定 总被引:3,自引:1,他引:3
在液体荧光法中用激光作激发光源大大提高了检测有机物和无机物的灵敏度。Полуэктов等在以汞灯为激发光源用钛铁试剂为铽的荧光试剂的液体荧光法中,测铽的检测限为4ppt。在同样条件下,他们也观察到了镝和钐的荧光,但由于其强度太弱,不能用于实际分析。在该法中,钛铁试剂与铽形成的二元络合物在紫外光连续照射下,其荧光强度逐渐下降,给测量带来不利影响。本工作同样采用钛铁试剂为荧光试剂,以氮分子激光 相似文献
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We review our research on the synthesis and study of the physical and biological properties of furyl- and thienylgermatranes and -silatranes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 725–732, June, 1992. 相似文献
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David W. Murhammer 《Applied biochemistry and biotechnology》1991,31(3):283-292
The use of the insect cell/baculovirus expression system for producing recombinant proteins of bacterial, plant, insect, and mammalian origin has become widespread. The popularity of this eukaryotic expression system is due to many factors, including (1) potentially high protein expression levels, (2) ease and speed of genetic engineering, (3) ability to accommodate large DNA inserts, (4) protein processing similar to higher eukaryotic cells (e.g., mammalian cells), and (5) ease of insect cell growth (e.g., suspension growth). The following review of the literature discusses two engineering aspects of recombinant protein synthesis by insect cell cultures: bioreactor scale-up and insect cell line selection. Following this review patent abstracts and additional literature pertaining to expression of recombinant proteins in insect cell culture are listed. 相似文献
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多环芳二酐型聚酯亚胺膜的透气性能李悦生,丁孟贤,徐纪平(浙江大学高分子科学与工程研究所,杭州,310027)(中国科学院长春应用化学研究所)关键词聚醚酰亚胺,聚酯酰亚胺,膜,透气性通常的聚酰亚胺加工性能较差,在芳环二酐的苯环间引入醚键等柔性基团后,其... 相似文献
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微量元素与疾病诊断治疗的研究现状及展望 总被引:8,自引:0,他引:8
对国内外微量元素与疾病的关系及其诊断治疗的研究现状及研究动向进行了综述,包括:微量元素与地方病、癌肿、心血管病、糖尿病、眼病、神经系统病等。参考文献72篇。 相似文献
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I. Luk
J. Pilka M. Kulí
kov P. Hrdlovi
《Journal of polymer science. Part A, Polymer chemistry》1977,15(7):1645-1653
Poly-p-ethylacrylophenone (PPEtAP) and poly-p-chloroacrylophenone (PPClAP) and their copolymers with styrene (PEtAP/S) and (PClAP/S) and with methyl methacrylate (PEtAP/MMA) and (PClAP/MMA) were prepared. Quantum yields of main-chain scissions at 366 nm at room temperature in benzene solution are of the same order as those of the unsubstituted polyacrylophenone and its copolymers. Substitution with chlorine and ethyl group in the para position compared to the unsubstituted polyacrylophenone and its copolymers leads to an increase of the lifetime for the n–π* excited triplet state, as is evident from the measured quenching constants of photolysis. The low-temperature emission spectra of the copolymers are similar to the spectra of the model compounds in a polymer film. For the homopolymer, however, the character of the emission spectrum changes considerably. 相似文献
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Concentrations and distributions of trace and minor elements in Chinese and Canadian coals and ashes
A total of 35 trace and minor elements including some of environmental significance were determined in each of a selection of 15 Chinese and 6 Canadian thermal coals and their ashes by using the SLOWPOKE-2 nuclear reactor facility of the University of Toronto. The concentrations and distributions of these constituents among the coals and their combustion products (viz. ash and volatile matter) are presented together with an interpretation of their significance in relation to the large scale combustion of these coals as thermal fuels in industrialized countries such as China and Canada. The detailed results showed wide variations in trace impurity concentrations (up to a factor of 100 and more) among the coals studied with few large differences between those of Chinese and Canadian origin except that the rare earths, Sc, Th, U, I, and Se were much higher in the former, other halogens, As and Na were lower. Values for elemental enrichment factors (EF) relative to normal crustal abundances indicated that only As(EF=13), Br(5.7), I(16), S(230), Sb(11) and Se(320) were appreciably enriched in coal. During static ashing at 750°C most of the halogens, S and Se were volatilized whereas most other inorganic constituents were highly retained and concentrated in the ash by factors of 6 to 11. 相似文献
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Karadakov PB 《The journal of physical chemistry. A》2008,112(31):7303-7309
The aromaticity and antiaromaticity of the ground state (S 0), lowest triplet state (T 1), and first singlet excited state (S 1) of benzene, and the ground states (S 0), lowest triplet states (T 1), and the first and second singlet excited states (S 1 and S 2) of square and rectangular cyclobutadiene are assessed using various magnetic criteria including nucleus-independent chemical shifts (NICS), proton shieldings, and magnetic susceptibilities calculated using complete-active-space self-consistent field (CASSCF) wave functions constructed from gauge-including atomic orbitals (GIAOs). These magnetic criteria strongly suggest that, in contrast to the well-known aromaticity of the S 0 state of benzene, the T 1 and S 1 states of this molecule are antiaromatic. In square cyclobutadiene, which is shown to be considerably more antiaromatic than rectangular cyclobutadiene, the magnetic properties of the T 1 and S 1 states allow these to be classified as aromatic. According to the computed magnetic criteria, the T 1 state of rectangular cyclobutadiene is still aromatic, but the S 1 state is antiaromatic, just as the S 2 state of square cyclobutadiene; the S 2 state of rectangular cyclobutadiene is nonaromatic. The results demonstrate that the well-known "triplet aromaticity" of cyclic conjugated hydrocarbons represents a particular case of a broader concept of excited-state aromaticity and antiaromaticity. It is shown that while electronic excitation may lead to increased nuclear shieldings in certain low-lying electronic states, in general its main effect can be expected to be nuclear deshielding, which can be substantial for heavier nuclei. 相似文献