Four complexes [Pd(L)(bipy)Cl]·4H2O (1), [Pd(L)(phen)Cl]·4H2O (2), [Pt(L)(bipy)Cl]·4H2O (3), and [Pt(L)(phen)Cl]·4H2O (4), where L = quinolinic acid, bipy = 2,2’-bipyridyl, and phen = 1,10-phenanthroline, have been synthesized and characterized using IR, 1H NMR, elemental analysis, and single-crystal X-ray diffractometry. The binding of the complexes to FS-DNA was investigated by electronic absorption titration and fluorescence spectroscopy. The results indicate that the complexes bind to FS-DNA in an intercalative mode and the intrinsic binding constants K of the title complexes with FS-DNA are about 3.5?×?104 M?1, 3.9?×?104 M?1, 6.1?×?104 M?1, and 1.4?×?105 M?1, respectively. Also, the four complexes bind to DNA with different binding affinities, in descending order: complex 4, complex 3, complex 2, complex 1. Gel electrophoresis assay demonstrated the ability of the Pt(II) complexes to cleave pBR322 plasmid DNA. 相似文献
In this paper, a novel fluorescent sensor 1 for selective and sensitive detection of cysteine was developed based on a complex between bi‐8‐carboxamidoquinoline derivative ligand ( L ) and Cu2+. The interaction of Cu2+ with the ligand causes a dramatic fluorescence quenching most likely due to its high affinity towards Cu2+ and a ligand–metal charge transfer (LMCT) process. The in situ generated L–Cu 2 complex was utilized as a chemosensing ensemble for cysteine. In the presence of cysteine, the fluorophore, L , was released from L–Cu 2 complex because of the strong affinity of cysteine to Cu2+ via the Cu–S bond, leading to the fluorescence recovery of the ligand. The proposed displacement mechanism was confirmed by the results of mass spectrometry (MS) study. Under optimized conditions, the recovered fluorescence intensity is linear with cysteine concentrations in the range 1 × 10?6 mol/l to 8 × 10?6 mol/l. The detection limit for cysteine is 1.92 × 10?7 mol/l. Furthermore, the established method showed a highly sensitive and selective response to cysteine among the 20 fundamental α‐amino acids used as the building blocks of proteins, after Ni2+ was used as a masking agent to eliminate the interference of His. The proposed sensor is applicable in monitoring cysteine in practical samples with good recovery rate. 相似文献
The interactions between Hg2+, Ce3+, and the mixuure of Ce3+ and Hg2+, and DNA from fish intestine in vitro were investigated by using absorption spectrum and fluorescence emission spectrum.
The ultraviolet absorption spectra indicated that the addition of Hg2+, Ce3+, and the mixture of Ce3+ and Hg2+ to DNA generated an obviously hypochromic effect. Meanwhile, the peak of DNA at 205.2 nm blue-shifted and at 258.2 nm red-shifted.
The size of the hypochromic effect and the peak shift of DNA by metal ion treatments was Hg2+>Hg2++Ce3+>Ce3+. The fluorescence emission spectra showed that with the addition of Hg2+, Ce3+, and the mixture of Ce3+ and Hg2+ the emission peak at about 416.2 nm of DNA did not obviously change, but the intensity reduced gradually and the sequence
was Hg2+>Hg2++Ce2+>Ce3+. Hg2+, Ce3+, and the mixture of Ce3+ and Hg2+ had 1.12, 0.19, and 0.41 binding sites to DNA, respectively; the fluorescence quenching of DNA caused by the metal ions all
attributed to static quenching. The binding constants (KA) of binding siees were 8.98×104 L/mol and 1.02×104 L/mol, 5.12×104 L/mol and 1.10×103 L/mol, 6.66×104 L/mol and 2.36×103 L/mol, respectively. The results showed that Ce3+ could relieve the destruction of Hg2+ on the DNA structure. 相似文献
Measurements of the equilibrium and temperature-jump u.v., visible, and induced c.d. spectra of Methyl Orange (MO) in the presence of cyclomalto-octaose (γ-cyclodextrin, γ-CD) have been carried out. Three mechanistic steps were detected through the temperature-jump data (25.0°): where K1, K2, and K3 are 45 (±7), 2.0 (±1.1) × 106, and 6.1 (±2.5) × 103 dm3.mol?1, respectively, k2 = 9.4 (±5.1) × 109 dm3.mol?1.s?1, and k?2 = 4.8 (±0.8) × 103 s?1. The equilibrium u.v./visible data are also consistent with this reaction scheme. The high stability of the dimer inclusion complex (MO)2 · γ-CD compared to that of the monomer inclusion complex MO · γ-CD appears to be related to the annular diameter of γ-CD and demonstrates a degree of selectivity in cyclodextrin inclusion complexes. The (MO)2 · (γ-CD)2 complex also contains a dimer, included by both γ-CD molecules. 相似文献
Intermolecular interaction study of human serum albumin (HSA) with two anthraquinones i.e. danthron and quinizarin has been performed through fluorescence, UV-vis and CD spectroscopy along with docking analysis. The titration of drugs into HSA solution brought about the quenching of fluorescence emission by way of complex formation. The binding constants were found to be 1.51 × 104 L mol?1 and 1.70 × 104 L mol?1 at λexc = 280 nm while at λexc = 295 nm, the values of binding constants were 1.81 × 104 L mol?1 and 1.90 × 104 L mol?1 which hinted toward binding of both the drugs in the vicinity of subdomain IIA. Different temperature study revealed the presence of static quenching mechanism. Moreover, more effective quenching of the fluorescence emission was observed at λexc = 295 nm which also suggested that both the drug molecule bind nearer to Trp-214. Thermodynamic parameters showed that hydrophobic interaction was the major force behind the binding of drugs. The UV-vis spectroscopy testified the formation of complex in both the systems and primary quenching mechanism as static one. The changes in secondary structure and α-helicity in both the systems were observed by circular dichroism spectroscopy. Furthermore, molecular docking analysis predicted the probable binding site of drugs in subdomain IIA of HSA molecule. The types of amino acid residues surrounding the drug molecule advocated that van der Waals forces, hydrophobic forces and electrostatic forces played a vital role in the stabilization of drug-protein complex formed. 相似文献
Bone is one of the main target organs for the lanthanides (Ln). Biodistribution studies of Tm-based compounds in vivo showed that bone had significant uptake. But the effect of Tm3+ on primary mouse bone marrow stromal cells (BMSCs) has not been reported. So we investigated the effect and underlying mechanisms of Tm3+ on BMSCs. Cell viability, cell apoptosis, reactive oxygen species (ROS) level, lactate dehydrogenase (LDH) activity and mitochondrial membrane potential (MMP) were studied. The results indicated that Tm3+ increased the viability of BMSCs at concentrations of 1?×?10?7, 1?×?10?6, 1?×?10?5, and 1?×?10?4 mol/L in a dose-dependent manner, turned to decrease the viability of BMSCs at the highest concentration of 1?×?10?3 mol/L for 24, 48, and 72 h. Tm3+ at 1?×?10?3 mol/L promoted apoptosis of BMSCs, increased the ROS and LDH levels, and decreased MMP in BMSCs. Taken together, we demonstrated that Tm3+ at 1?×?10?3 mol/L might induce cellular apoptosis through mitochondrial pathway. These results may be helpful for more rational application of Tm-based compounds in the future. 相似文献
The binding of one fluorine including triazole (C10H9FN4S, FTZ) to bovine serum albumin (BSA) was studied by spectroscopic techniques including fluorescence spectroscopy, UV–Vis absorption, and circular dichroism (CD) spectroscopy under simulative physiological conditions. Fluorescence data revealed that the fluorescence quenching of BSA by FTZ was the result of forming a complex of BSA–FTZ, and the binding constants (Ka) at three different temperatures (298, 304, and 310 K) were 1.516?×?104, 1.627?×?104, and 1.711?×?104?mol L?1, respectively, according to the modified Stern–Volmer equation. The thermodynamic parameters ΔH and ΔS were estimated to be 7.752 kJ mol?1 and 125.217 J?mol?1?K?1, respectively, indicating that hydrophobic interaction played a major role in stabilizing the BSA–FTZ complex. It was observed that site I was the main binding site for FTZ to BSA from the competitive experiments. The distance r between donor (BSA) and acceptor (FTZ) was calculated to be 7.42 nm based on the Förster theory of non-radioactive energy transfer. Furthermore, the analysis of fluorescence data and CD data revealed that the conformation of BSA changed upon the interaction with FTZ. 相似文献