共查询到19条相似文献,搜索用时 421 毫秒
1.
本文通过分子生物学方法将八肋游仆虫中心蛋白N端半分子loop区的首个氨基酸,天冬氨酸Asp37和Asp73,分别突变为带相反电荷的赖氨酸。使用铽敏化荧光、TNS疏水探针研究了八肋游仆虫中心蛋白N端半分子loop区的首个氨基酸的作用。结果表明:当中心蛋白loop Ⅰ区37位的天冬氨酸突变为赖氨酸后,loop Ⅰ丧失了金属离子结合能力,进而影响了中心蛋白依赖于金属离子的构象变化;而loop Ⅱ区73位的天冬氨酸突变为赖氨酸后仍保持金属离子结合能力,依赖于金属离子的构象变化减小。中心蛋白发挥大部分生物功能都依赖于金属离子,这就表明loop Ⅰ区37位的天冬氨酸在中心蛋白发挥生物功能时起着重要作用,是不可缺少的。在10 mmol·L-1 Hepes、pH 7.4、20 mmol·L-1 KCl条件下,八肋游仆虫中心蛋白N端半分子loop Ⅱ与金属离子Tb3+和Ca2+的结合常数分别为:KⅡ(Tb3+)=(8.31±0.18)×104 L·mol-1和KⅡ(Ca2+)=(0.94±0.12)×102 L·mol-1,中心蛋白N端半分子的两个金属结合部位结合能力顺序为:Ⅰ>Ⅱ。 相似文献
2.
利用瞬态吸收光谱技术研究了不同条件下C6H5Cl与H2O2水溶液的激光闪光光解情况, 初步考察了其瞬态物种的生长和衰减等行为. 研究表明, •OH自由基和C6H5Cl反应生成C6H5Cl-OH adduct, 其反应速率常数在近中性、酸性条件下约为(5.89±0.65)×109和(7.07±0.61)×109 L•mol-1•s-1; 其衰减则符合双分子二级反应, 速率常数2k/εl=1.1×106 s-1, 而在碱性时则为(4.34±0.51)×109 L•mol-1•s-1, 衰减呈准一级反应, 速率常数为2.11×105 s-1. 在有氧条件下, O2与C6H5Cl-OH adduct反应生成C6H5Cl-OHO2 adduct, 其反应速率常数为6.8×108 L•mol-1•s-1. 相似文献
3.
本文通过酶活性测定,荧光光谱和紫外光谱研究了外加Cu2+与烟草多酚氧化酶(简称PPO)的相互作用。结果表明,微量铜的加入能增加酶的活性,[Cu2+]/[PPO]为0.20左右时酶活性最大,[Cu2+]/[PPO]为0.91时,Cu2+开始表现出对PPO活性的抑制;Cu2+对PPO内源荧光的猝灭机制属于形成络合物所引起的静态猝灭,猝灭常数Ksv为8.0375×103L·mol-1;Cu2+的加入使PPO蛋白质分子构象发生变化,α-螺旋含量增加,多肽链及Trp和Tyr残基的芳杂环进一步向分子内收缩,疏水基团之间的疏水作用增强。 相似文献
4.
应用荧光光谱、荧光显微镜和伏安法研究了乙醇/水体系中Cu(Ⅱ)对十二烷基硫酸钠(SDS)和鱼精DNA增强[Ru(bpy)2(dppz)]2+(bpy=2,2′-联吡啶, dppz=邻联二吡啶[3,2-a:2′,3′-c]吩嗪)光致发光的调控。结果表明, 在乙醇/三羟甲基氨基甲烷(Tris)-水 (V乙醇:VTris=1:5)体系中, DNA和阴离子表面活性剂SDS均能增强[Ru(bpy)2(dppz)]2+的光致发光, 其与[Ru(bpy)2(dppz)]2+间的键合常数分别为5.5×105和4.2×102 L·mol-1;Cu(Ⅱ)离子能通过DNA和SDS介导的光诱导电子转移淬灭乙醇/水溶液中[Ru(bpy)2(dppz)]2+的光致发光, DNA介导的Stern-Volmer淬灭常数为2.0×105 L·mol-1, 远远大于SDS介导的淬灭常数(9.0×103 L·mol-1)。此外, 结合SDS、DNA和Cu(Ⅱ)对[Ru(bpy)2(dppz)]2+在铟锡氧化物(ITO)电极上发生的氧化还原反应的影响, 进一步探讨了乙醇/Tris-水中Cu(Ⅱ)对SDS和DNA增强[Ru(bpy)2(dppz)]2+光致发光的调控机理。该研究有助于更好地理解DNA嵌入剂的发光和淬灭机制, 为生物分子光开关的构建提供新思路。 相似文献
5.
杂多酸盐K7[PTi2W10O40]·6H2O与牛血清白蛋白相互作用的研究 总被引:7,自引:0,他引:7
Under the imitated physiological condition of animal body, the interactions of heteropoly salt (PM-19) with bovine serum albumin (BSA) were investigated by fluorescence and absorption spectroscopy. It was shown that this compound had a quite strong ability to quench the fluorescence launching from BSA. After analyzing the fluorescence quenching data according to Stern-Volmer equation and Lineweaver-Burk double-reciprocal equation, we found that BSA had reacted with PM-19 and formed a certain new compound. The quenching belonged to static fluorescence quenching. According to Lineweaver-Burk equation, the forming constants of the compound (298 K: 2.68 × 105 L·mol-1; 304 K: 2.19 × 105 L·mol-1; 310 K: 1.82 × 105 L·mol-1) and the thermodynamic parameters (ΔH=-24.72 kJ·mol-1; ΔS=20.97 J·mol-1·K-1 / 20.92 J·mol-1·K-1/ 20.97 J·mol-1·K-1; ΔG=-30.97 kJ·mol-1/ -31.08 kJ·mol-1/-31.22kJ·mol-1) at the corresponding temperatures were obtained. The latter shows that binding power between them is mainly electrostatic interaction. Based on F?rster′s non-radiation energy transfer mechanism, the binding locality (r=4.14 nm) was calculated between donor and accepter. The effect of PM-19 on the conformation of BSA was also analyzed by synchronous fluorescence spectroscopy. 相似文献
6.
7.
以咔唑为原料,经过两步反应制备得到N-乙基咔唑-3-甲醛,其结构经X射线单晶衍射测定属于单斜晶系,空间群为P21/n。再以N-乙基咔唑-3-甲醛与1,3-二氨-2-丙醇为原料,设计、合成了一种新型双席夫碱荧光探针分子CMP。借助荧光光谱在体积比为6∶4的DMSO/H2O缓冲溶液(Tris-HCl,pH=7.0)中研究了探针CMP对Cu2+的选择性识别。研究结果表明,探针CMP与Cu2+以1∶2的比例配位,结合常数为1.52×105 L·mol-1,检出限为0.205 μmol·L-1。回收实验表明,探针分子CMP可应用于环境水样中Cu2+的检测。 相似文献
8.
利用瞬态吸收光谱技术研究了不同条件下C6H5Cl与H2O2水溶液的激光闪光光解情况, 初步考察了其瞬态物种的生长和衰减等行为. 研究表明, •OH自由基和C6H5Cl反应生成C6H5Cl-OH adduct, 其反应速率常数在近中性、酸性条件下约为(5.89±0.65)×109和(7.07±0.61)×109 L•mol-1•s-1; 其衰减则符合双分子二级反应, 速率常数2k/εl=1.1×106 s-1, 而在碱性时则为(4.34±0.51)×109 L•mol-1•s-1, 衰减呈准一级反应, 速率常数为2.11×105 s-1. 在有氧条件下, O2与C6H5Cl-OH adduct反应生成C6H5Cl-OHO2 adduct, 其反应速率常数为6.8×108 L•mol-1•s-1. 相似文献
9.
Pyoverdine A(PvdA)是荧光假单胞菌分泌的一种水溶性较高的黄绿色荧光铁载体。在50mmol·L-1Tris-HCl,pH8.0条件下,使用紫外-可见吸收差光谱、荧光光谱研究了铽(Ⅲ)与荧光铁载体PvdA的结合。结果表明铽(Ⅲ)可与PvdA结合形成1:1的配合物,条件结合常数为(4.44±0.82)×1014mol-1·L。在生理条件下,PvdA可竞争伴清蛋白N-,C-端结合的铽(Ⅲ)形成Tb-PvdA配合物;Tb-PvdA与荧光假单胞菌细胞表面受体FpvA结合形成Tb-PvdA-FpvA复合物。 相似文献
10.
合成了3个新的SOD模拟配合物:[Cu(Phen)(L-Gln)(H2O)]Cl·2H2O
(1)、[Cu(Phen)(L-Ala)(H2O)]Cl·4H2O (2)、[Cu(Phen)(L-Thr)(H2O)]Cl·2H2O
(3) [Phen(1,10-邻菲咯啉)、L-Gln(谷氨酰胺)、L-Ala(丙氨酸)、L-Thr(苏氨酸)]。用元素分析、摩尔电导、红外光谱、紫外-可见光谱对配合物进行了表征。用X-射线衍射对配合物[Cu(Phen)(L-Gln)(H2O)]Cl·2H2O的晶体结构进行了测定。用氯化硝基四氮唑蓝(NBT)光还原法对这3个配合物催化歧化超氧阴离子自由基(O2- ·)的能力进行了测定。结果表明:这些配合物具有较高的SOD活性, 催化速率常数KQ分别为1.58 ×
107 mol-1·L·s-1、5.65 × 107 mol-1·L·s-1、0.83 ×
107 mol-1·L·s-1。 相似文献
11.
Keli Zhong Jie Zhao Xue Zhou Shuhua Hou Yanjiang Bian Jianrong Li Lijun Tang 《中国化学》2016,34(12):1329-1334
A new (8‐hydroxyquinolin‐2‐yl)methylene picolinohydrazide derivative ( L ) has been successfully synthesized and characterized. The probe L displays high selectivity to Co2+ in CH3CN/HEPES (1:1, V/V, 10 mmol·L?1, pH=7.4) with a fluorescence "ON‐OFF" response. The Co2+ ion recognition event possesses some distinct features including rapid response, high selectivity and sensitivity, good anti‐interference ability and being applicable within a wide pH range. Based on job's plot and ESI‐MS studies, the 1:1 binding mode was proposed. The binding constant of L and Co2+ is 1.63×108 L·mol?1 and the detection limit is 1.15 µmol·L?1. Natural water samples experiments revealed that probe L can be potentially applied to the detection of Co2+ in real environment. 相似文献
12.
Pyoverdine A(PvdA)是荧光假单胞菌分泌的一种水溶性较高的黄绿色荧光铁载体。在50 mmol·L-1Tris-HCl,pH 8.0条件下,使用紫外-可见吸收差光谱、荧光光谱研究了铽(Ⅲ)与荧光铁载体PvdA的结合。结果表明铽(Ⅲ)可与PvdA结合形成1:1的配合物,条件结合常数为(4.44±0.82)×1014mol-1·L。在生理条件下,PvdA可竞争伴清蛋白N-,C-端结合的铽(Ⅲ)形成Tb-PvdA配合物;Tb-PvdA与荧光假单胞菌细胞表面受体FpvA结合形成Tb-PvdA-FpvA复合物。 相似文献
13.
铝(Ⅲ)与脱铁伴清蛋白结合的紫外差光谱研究 总被引:2,自引:0,他引:2
在 pH7.4、 0.1mol· L~(-1)N-2-羟乙基哌嗪- N′-2-乙磺酸( Hepes)及室温条件下,使用紫外吸收差光谱进行了铝(Ⅲ)对脱铁伴清蛋白的滴定。结果表明铝(Ⅲ)与脱铁伴清蛋白结合后其紫外差光谱在 238nm和 291nm处出现吸收峰。在 238nm处铝(Ⅲ)-脱铁伴清蛋白配合物的摩尔吸光系数是 (1.52± 0.04)× 10~4cm~(-1)· mol~(-1)· L。铝(Ⅲ)可占据脱铁伴清蛋白的两个金属离子结合部位,条件稳定常数是 lgK_N=11.21± 0.12,lgKC=9.53± 0.24。 N-端单铁伴清蛋白的紫外差光谱滴定表明,铝 ?优先占据脱铁伴清蛋白的 N端结合部位。 相似文献
14.
利用固相多肽合成法合成了一种新的多肽,将该多肽与荧光基团Dansyl偶联制备了一种新的荧光化学比率传感器:Dansyl-Cys-Pro-Pro-Cys-Trp-NH2。利用荧光光谱研究了它与金属离子的相互作用。结果表明,与其它13种金属离子相比该多肽对金属Cd2+有很好的选择性。它能特异性识别Cd2+,具有水溶性好,响应时间快等优点。该肽对Cd2+具有很强的键合作用,其结合常数为3.0×1011 L2·mol-2,检出限为11.5 nmol·L-1。 相似文献
15.
The interaction between mercuric ion and apoCopC in the absence or presence of cupric ion was investigated through difference UV spectra in Hepes buffer (10 mmol·L^-1) at pH 7.4. The results suggest that mercuric ion can bind to C- and N-terminal binding sites of apoCopC, and the conditional binding constants were calculated to be kN=(6.79± 1.12)× 10^6 mol^-1·L and kc=(3.06±0.05)× 10^5 mol^-1·L. Using urea as a chemical agent, the conformational stabilities of apoCopC and HgN^2+ -CopC-Hgc^2+ were monitored by fluorescence spectrum in Hepes buffer (50 mmol·L^-1) at pH 7.4. The free energy of stabilization is (14.69±0.85) and (16.66±0.55) kJ.mol^-1, respectively. HgN^2+ -CopC-Hgc^2+ is more stable than apoCopC. 相似文献
16.
Jie Ma Yulan Zeng Luliang Yan Bingkun Chen Mengya Sun Zhenhua Liu 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):582-586
AbstractA fluorescent sensor TPE-TSC with aggregation induced emission (AIE) characteristic is synthesized for detecting Hg2+ by attaching thiosemicarbazide (TSC) unit into tetraphenylethylene (TPE) group. TPE-TSC exhibits intense green emission in DMSO/H2O (V:V?=?1:9) solution with the formation of the aggregation. TPE-TSC shows outstanding fluorescence quenching toward Hg2+ over other metal ions due to the formation of complex TPE-TSC/Hg2+ with a 2:1 binding ratio. The detection limit of TPE-TSC for Hg2+ is 1?×?10?5 mol·L?1. 相似文献
17.
Qingxian Liao Aifang Li Zhao Li Yibin Ruan Yunbao Jiang 《Frontiers of Chemistry in China》2010,5(2):178-183
A selective and sensitive intramolecular charge transfer (ICT) fluorescent chemosensor was designed for Cu2+ in neutral aqueous solutions of pH 7.0. The design of this totally water-soluble fluorescent chemosensor was based on the
binding motif of Cu2+ to aminoacid, which is coupled to an ICT fluorophore bearing a 1,3,4-thiodiazole moiety in the electron acceptor. The formation
of a 1:1 complex of Cu2+ to 2 was suggested to lead to fluorescence quenching. The quenching obeyed Stern-Volmer theory in neutral aqueous solution
of pH 7.0 for Cu2+ over 5.0 × 10−7 to 3.0 × 10−5 mol·L−1, with a quenching constant of 1.8 × 105 L·mol−1 and a detection limit of 2.0 × 10−7 mol·L−1. The binding of Cu2+ to 2 can be fully reversed by addition of chelator EDTA, affording a reversible sensing performance. 相似文献
18.
A luminescent lanthanide-organic framework [Eu2(adip)(H2adip)(DMF)2]·CH3OH ( 1 ) was synthesized by a solvothermal method using anthracene-based ligand 5,5’-(anthracene-9,10-diyl)diisophthalic acid (H4adip). 1 possesses a 3D coordination framework, which could be rationalized as a 4,8-connected 2-nodal (416612)(4462) topological network. 1 shows an excellent linear increase in fluorescence intensity as the pH value rises from 4.8 to 7.1. Particularly, the fluorescence enhancement percentage reaches 588% for each increase of pH value, which is the highest value recorded for fluorescence pH sensing materials, promoting the sensitivity of pH detection within the physiological pH range. In addition, 1 can also specifically recognize carbon disulfide biomarkers 2-thiothiazolidine-4-carboxylic acid (TTCA) and antibiotic aztreonam (ATM) by fluorescence quenching, with the KSV values of 1.02 × 105 L·mol–1 (0—10 μmol·L–1) and 4.67 × 105 L·mol–1 (0—50 μmol·L–1), the limit of detection (LOD) of 86 nmol·L–1 and 19 nmol·L–1, respectively. Among only a few cases reported, the detection sensitivities of 1 for both TTCA and ATM are the highest. The sensing mechanisms of pH, TTCA, and ATM are also discussed in detail. 相似文献
19.
Mahendra Sonawane Kundan Tayade Suban K. Sahoo Chatur P. Sawant 《Journal of Coordination Chemistry》2016,69(18):2785-2792
A new lawsone-based azo-dye 2-hydroxy-3-((pyridin-2-ylmethyl)diazenyl)naphthalene-1,4-dione (1) was synthesized and applied for sensing of metal ions. Receptor 1 showed selective fluorescent and colorimetric response for the detection of Cu2+ and Fe3+ over other tested metal ions. The fluorescence intensity of 1 was significantly quenched allowing detection of Fe3+ and Cu2+ down to 0.61 and 6.06 μM, respectively. The binding has been established by fluorescence spectroscopic method. Receptor 1 provided a 1?:?1 binding scaffold for recognition of Fe3+ and Cu2+ ions with the association constant of 3.33 × 106 and 3.33 × 105 M?1, respectively. The B3LYP/6-31G/LANL2DZ method was employed for the optimization of 1 and 1·Fe3+ and 1·Cu2+. 相似文献