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101.
在模拟生理条件下,运用荧光光谱、激光闪光光解(LFP)和分子对接等技术研究了8种具有抗肿瘤活性的嘧啶衍生物(PDs,其中PDs A 5-FU为成药,PDs B-H为实验室自制)与人血清白蛋白(HSA)的相互作用.利用Stern-Volmer方程和激光闪光光解技术分析了PDs对HSA的荧光猝灭机制,PDs A和B为静态猝灭,PDs G和H为动态猝灭.用双倒数曲线法得出5种PDs与HSA的结合常数Ka和结合位点数n,在测定条件下5种PDs与载体结合位点数均为1,且均以弱结合力结合,通过热力学参数ΔH,ΔS和ΔG推测出PDs B,C和E与HSA之间的作用力为静电作用力和疏水作用力,PDs A和D与HSA之间的作用力是氢键和范德华力,分子对接结果与其一致.根据F9rster非辐射能量转移理论(FRET)分析了HSA和PDs之间的结合距离(r),其结果均小于4 nm,符合能量转移理论.进一步利用同步荧光、三维荧光和圆二色光谱考察了PDs与HSA结合过程中HSA空间构象的变化,结果显示,仅PDs A和C对HSA的芳香族氨基酸周围的疏水性略有增强作用.体外实验结果表明,HSA可以作为优良的载体来运输和储存PDs A~E,这为嘧啶衍生物的后续研究提供了可参考的实验数据. 相似文献
102.
Li Ruifen Cao Xiaojun Zhao Haogui Liu Chunxia Li Zheng Wang Jinhua Zhang Lan Li Qinguan 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(3):1715-1725
Di-1-methyl heptyl methyl phosphonate (DMHMP) is a promising alternative extractant for Th-U fuel reprocessing, in which the irradiation stability of extractant should be systematically studied. In this paper, the radiolysis products of DMHMP were analyzed qualitatively and quantitatively with gas and ion chromatograph, the possible radiolysis mechanism of DMHMP was also concluded. Moreover, the effect of structure on the radiolysis products and irradiation stability of neutral organophosphorus compound extractant was also discussed.
相似文献103.
Xuliang Lin Cheng Cai Hongming Lou Xueqing Qiu Yuxia Pang Dongjie Yang 《Cellulose (London, England)》2017,24(1):61-68
Effect of cationic surfactants alkyltrimethylammonium bromide (CnTAB) with varied alkyl chain lengths on the enzymatic hydrolysis of Avicel and the surface charge of cellulase was investigated. Enzymatic hydrolysis of Avicel increased linearly from 42.1 to 61.4 % with the increase of the concentration of cetyltrimethylammonium bromide (C16TAB) logarithmically from 0.0001 to 0.01 mM, and reached a maximum value at the concentration of 0.01–0.03 mM. When the concentration was increased further, the cellulase solution became positively charged and the enzymatic hydrolysis of Avicel decreased rapidly. With the increasing alkyl chain length, CnTAB provided more proton and neutralized the negative charge of cellulase more obviously. Therefore, the required concentration of CnTAB could be less to enhance the enzymatic hydrolysis of Avicel. In addition, C16TAB could enhance enzymatic hydrolysis efficiency of corncob at high solid content from 35.0 to 56.3 %; C16TAB could reduce about 60 % of the cellulase loading in the enzymatic hydrolysis of corncob to obtain the same glucose yield. Effect of C16TAB on the enzymatic hydrolysis of typical pretreated softwood and hardwood was also investigated. This study laid the foundation for using CnTAB to recover cellulase, and provided the design direction for cellulase with higher activity and better stability by adjusting its hydrophilicity and chargeability. 相似文献
104.
105.
The chemical bonding and spectral assignments of rhodium(III)‐catalyzed closo‐dodecaborate complexes: Ab initio study 下载免费PDF全文
Xiaojun Li Xiaohui Yang Hongjiang Ren Ping Sun Zhenhua Fang 《International journal of quantum chemistry》2017,117(19)
The chemical bonding and spectral assignments of rhodium(III)‐catalyzed closo‐dodecaborate (RhCD) complex are systematically studied using the density functional theory calculations. It is found that the calculated main bond lengths of framework are in good agreement with experimental X‐ray observation, and the pronounced hybridization of B‐2p and Rh‐4d states is responsible for the structural stability, reflected by the large dissociation energy and HOMO–LUMO energy gap. The AdNDP chemical bonding analysis indicates that the RhCD complex can be stabilized by two H‐bridged 3c‐2e σ‐bonds (B‐H‐Rh triangles). Additionally, the theoretical calculations reproduce well the main experimental IR spectrum, and the characteristic peaks are properly assigned. These results will be helpful for further insight into the unique electronic structure of the species, and provide valuable references for potential applications in novel materials. 相似文献
106.
Wen-Li Zhou Hai-Bo Tan Sheng-Xiang Qiu Guang-Ying Chen Hong-Xin Liu Chao Zheng 《Tetrahedron letters》2017,58(19):1817-1821
A confirmed structure of meroterpenoid myrtucommulone K, which is vastly different from the originally reported one, is conducted. The first biomimetic total synthesis towards the assignment of its absolute configuration has been efficiently accessed in 5 steps, and key to the success was a heteroatom Diels-Alder cycloaddition. The structure of myrtucommulone K was re-elucidated and confirmed by extensive spectroscopic interpretation of 1D and 2D NMR. 相似文献
107.
N-Heterocyclic carbene-catalyzed 1,6-addition of aromatic aldehydes to para-quinone methides has been developed. This method could efficiently furnish α,α′-diarylated ketones with good to high yields, which contain various functional groups. 相似文献
108.
Triphenylphosphine-mediated metal-free trifluoromethylthiolation and difluoromethylthiolation of thiols by CF3SO2Cl and CHF2SO2Cl to synthesize trifluoromethyl disulfides and difluoromethyl disulfides, respectively, was achieved at room temperature. Iodine generated in situ from iodide facilitated this reaction via the formation of iodotriphenylphosphonium iodide which could serve as a reducing agent in this transformation. Readily available reagents and mild reaction conditions without transition-metals allow this protocol to be more practical than traditional methods. 相似文献
109.
An efficient and thermally induced reaction of diazoamide with isatin under mild reaction conditions is described, which provides a complementary approach to the 3,3′-bioxindole in high yields with excellent diastereoselectivity. In comparison to the metal-catalyzed versions, this is the only example under catalyst-free conditions via a non-carbene reaction pathway. 相似文献
110.
Zebin?Guo Yafeng?Zheng Hui?Xu Baodong?ZhengEmail author Wanwei?Qiu Guodong?LiuEmail author 《Mikrochimica acta》2017,184(11):4243-4250
The authors describe an oligonucleotide-based lateral flow test for visual detection of Ag(I). The assay is based on cytosine-Ag(I)-cytosine [C-Ag(I)-C] coordination chemistry to capture gold nanoparticle (AuNP) tags in the test zone. A thiolated C-rich oligonucleotide probe was immobilized on the AuNPs via gold-thiol chemistry, and a biotinylated C-rich oligonucleotide probe was immobilized on the test zone. The AuNPs labelled with C-rich oligonucleotides are captured by Ag(I) ions in the test zone through the C-Ag(I)-C coordination. The resulting accumulation of AuNPs produces a readily visible red band in the test zone. Under optimized conditions, the test is capable of visually detecting 1.0 ppb of Ag(I) which is 50 times lower than the maximum allowable concentration as defined by the US Environmental Protection Agency for drinking water. Hence, the test is inexpensive and highly sensitive. It was applied to the detection of Ag(I) in spiked samples of tap water and river water. In our perception, the test is a particularly valuable tool in limited resource settings. 相似文献