scholarly journals Synthesis, Characterization and DNA-Binding Affinity of a New Zinc(II) Bis(5-methoxy-indol-3-yl)propane-1,3-dione Complex

2021 ◽  
Vol 14 (8) ◽  
pp. 760
Author(s):  
Luca Scapinello ◽  
Guglielmo Vesco ◽  
Luca Nardo ◽  
Angelo Maspero ◽  
Federico Vavassori ◽  
...  
Keyword(s):  
Metal Ion ◽  
Structural Changes ◽  
Fluorescence Emission ◽  
Spectroscopic Techniques ◽  
Time Resolved ◽  
Fluorescence Studies ◽  
High Affinity ◽  
Drug Substances ◽  
Calf Thymus

The novel zinc(II) µ-oxo-bridged-dimeric complex [Zn2(µ-O)2(BMIP)2] (BMIP = 1,3-bis(5-methoxy-1-methyl-1H-indol-3-yl)propane-1,3-dione), 1, was synthetized and fully characterized. The spectral data indicate a zincoxane molecular structure, with the BMIP ligand coordinating in its neutral form via its oxygen atoms. Structural changes in 1 in dimethylsulfoxide (DMSO) were evidenced by means of spectroscopic techniques including infrared absorption and nuclear magnetic resonance, showing DMSO entrance in the coordination sphere of the metal ion. The resulting complex [Zn2(µ-O)2(BMIP)2(DMSO)], 2, readily reacts in the presence of N-methyl-imidazole (NMI), a liquid-phase nucleoside mimic, to form [Zn2(µ-O)2(BMIP)2(NMI)], 3, through DMSO displacement. The three complexes show high thermal stability, demonstrating that 1 has high affinity for hard nucleophiles. Finally, with the aim of probing the suitability of this system as model scaffold for new potential anticancer metallodrugs, the interactions of 1 with calf thymus DNA were investigated in vitro in pseudo-physiological environment through UV-Vis absorption and fluorescence emission spectroscopy, as well as time-resolved fluorescence studies. The latter analyses revealed that [Zn2(µ-O)2(BMIP)2(DMSO)] binds to DNA with high affinity upon DMSO displacement, opening new perspectives for the development of optimized drug substances.

scholarly journals New homodi-and heterotrinuclear metal complexes of Schiff base compartmental ligand: interaction studies of copper complexes with calf thymus DNA

2006 ◽  
Vol 4 (3) ◽  
pp. 502-522 ◽  
Author(s):  
Suvigya Mathur ◽  
Sartaj Tabassum
Keyword(s):  
Schiff Base ◽  
Metal Complexes ◽  
Metal Ion ◽  
Chloride Ions ◽  
Calf Thymus Dna ◽  
Planar Geometry ◽  
Spectroscopic Techniques ◽  
Ligand Interaction ◽  
Fluorescence Studies ◽  
Calf Thymus

AbstractThe new homodinuclear complexes 1–4 of the type [LMII 2Cl2], heterotrinuclear complexes 5 and 6 of the type [LMII 2SnIVCl6] where M = CuII, MnII, CoII, NiII and CuII and NiII, respectively have been synthesized and characterized by elemental analysis and various spectroscopic techniques. The homodinuclear complexes possess two different environments (N2 and N2O2donor sets) for holding the metal ions. The metal ion in N2 set exhibits square planar geometry with two chloride ions in the inner sphere but rhombic structure is found in tetradentate N2O2 Schiff base cavity while in heterotrinuclear complexes SnIV atom is in the octahedral environment. The interaction of complexes 1 and 5 with calf thymus DNA was carried out by absorption spectroscopy and cyclic voltammetry. The intrinsic binding constants (K b) of complex 1 and 5 were determined as 3.2 × 103 M−1 and 9.6 × 103 M−1, respectively suggesting that complex 5 binds more strongly to CT-DNA than complex 1. Fluorescence studies along with viscosity measurements have also been checked to authenticate the binding of metal complexes with DNA.

scholarly journals Interaction of polyethylene glycol with cytochrome c investigated via in vitro and in silico approaches

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zahoor Ahmad Parray ◽  
Faizan Ahmad ◽  
Mohamed F. Alajmi ◽  
Afzal Hussain ◽  
Md. Imtaiyaz Hassan ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Structural Changes ◽  
Apoptotic Cell ◽  
Titration Calorimetry ◽  
Spectroscopic Techniques ◽  
Tertiary Structures ◽  
Time Resolved ◽  
Soft Interactions ◽  
And Control

AbstractOne of the significant proteins that have attracted research groups due to virtue of being a potent selective anticancer drug target and property of triggering apoptosis upon release in cytoplasm is cytochrome c (cyt c). The mechanical transformations due to the macromolecular crowding in membrane in the mammalian cell are proposed to be useful inductors of changes in volume. It is very interesting to know that mitochondrial function were observed to be improved by polyethylene glycol (PEG) interaction, which in turn inhibits the cyt c (a pro-apoptotic cell death factor). In this work, the effect of polyethylene glycol of molecular weight 4 kilo Dalton (PEG 4 kDa) was investigated to highlight the structural transformations (tertiary and secondary structure) in cyt c using a choice of spectroscopic techniques (including UV–Vis absorption, near-UV, far-UV and Soret circular dichroism and fluorescence spectroscopy), which shows noteworthy shifts in the secondary and tertiary structures at higher concentrations of PEG 4 kDa with small changes in the heme-globular interactions. The size distribution changes of native protein treated with various concentrations of the crowder were observed and analyzed by dynamic light scattering (DLS). The interaction studies of the crowder with the protein was observed and analyzed by FTIR, isothermal titration calorimetry, time resolved fluorescence and molecular docking. The investigations suggested that the structural changes in the protein occurred due to soft interactions of PEG 4 kDa, which usually destabilizes proteins. The experimental evidence in this study proposed that crowding could be another approach to mechanical super-competition and free of certain markers that could aid in the identification and control of various diseases. This study suggests that crowders at specific concentrations, which softly interact with proteins, can be exploited as remedy for various diseases.

scholarly journals Synthesis and Characterisation of Copper(II) Complexes with Tridentate NNO Functionalized Ligand: Density Function Theory Study, DNA Binding Mechanism, Optical Properties, and Biological Application

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Madhumita Hazra ◽  
Tanushree Dolai ◽  
Akhil Pandey ◽  
Subrata Kumar Dey ◽  
Animesh Patra
Keyword(s):  
Density Function ◽  
Antimicrobial Agents ◽  
Function Theory ◽  
Free Ligand ◽  
Fluorescence Emission ◽  
Building Blocks ◽  
Density Function Theory ◽  
Calf Thymus Dna ◽  
Spectroscopic Techniques ◽  
Calf Thymus

The photo physical properties of two mononuclear pentacoordinated copper(II) complexes formulated as [Cu(L)(Cl)(H2O)] (1) and [Cu(L)(Br)(H2O)] (2)HL = (1-[(3-methyl-pyridine-2-ylimino)-methyl]-naphthalen-2-ol) were synthesized and characterized by elemental, physicochemical, and spectroscopic methods. The density function theory calculations are used to investigate the electronic structures and the electronic properties of ligand and complex. The interactions of copper(II) complexes towards calf thymus DNA were examined with the help of absorption, viscosity, and fluorescence spectroscopic techniques at pH 7.40. All spectroscopy's result indicates that complexes show good binding activity to calf thymus DNA through groove binding. The optical absorption and fluorescence emission properties of microwires were characterized by fluorescence microscope. From a spectroscopic viewpoint, all compounds strongly emit green light in the solid state. The microscopy investigation suggested that microwires exhibited optical waveguide behaviour which are applicable as fluorescent nanomaterials and can be used as building blocks for miniaturized photonic devices. Antibacterial study reveals that complexes are better antimicrobial agents than free Schiff base due to bacterial cell penetration by chelation. Moreover, the antioxidant study of the ligand and complexes is evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical assays, which demonstrate that the complexes are of higher antioxidant activity than free ligand.

scholarly journals Critical binding and regulatory interactions between Ras and Raf occur through a small, stable N-terminal domain of Raf and specific Ras effector residues.

1994 ◽  
Vol 14 (8) ◽  
pp. 5318-5325 ◽  
Author(s):  
E Chuang ◽  
D Barnard ◽  
L Hettich ◽  
X F Zhang ◽  
J Avruch ◽  
...  
Keyword(s):  
Structural Changes ◽  
Regulatory Region ◽  
Ras Proteins ◽  
Binding Region ◽  
Raf Kinase ◽  
High Affinity ◽  
Critical Binding ◽  
Kinase Pathway ◽  
Zinc Finger Region

Genetic and biochemical evidence suggests that the Ras protooncogene product regulates the activation of the Raf kinase pathway, leading to the proposal that Raf is a direct mitogenic effector of activated Ras. Here we report the use of a novel competition assay to measure in vitro the relative affinity of the c-Raf-1 regulatory region for Ras-GTP, Ras-GDP, and 10 oncogenic and effector mutant Ras proteins. c-Raf-1 associates with normal Ras and the oncogenic V12 and L61 forms of Ras with equal affinity. The moderately transforming mutant Ras[E30K31] also bound to the c-Raf-1 regulatory region with normal affinity. Transformation-defective Ras effector mutants Ras[N33], Ras[S35], and Ras[N38] bound poorly. In contrast, the transformation defective Ras[G26I27] and Ras[E45] mutants bound to the c-Raf-1 regulatory region with nearly wild-type affinity. A stable, high-affinity Ras-binding region of c-Raf-1 was mapped to a 99-amino-acid subfragment of the first 257 residues. The smallest Ras-binding region identified consisted of N-terminal residues 51 to 131, although stable expression of the domain and high-affinity binding were improved by the presence of residues 132 to 149. Deletion of the Raf zinc finger region did not reduce Ras-binding affinity, while removal of the first 50 amino acids greatly increased affinity. Phosphorylation of Raf[1-149] by protein kinase A on serine 43 resulted in significant inhibiton of Ras binding. demonstrating that the mechanism of cyclic AMP downregulation results through structural changes occurring exclusively in this small Ras-binding domain.

Critical binding and regulatory interactions between Ras and Raf occur through a small, stable N-terminal domain of Raf and specific Ras effector residues

1994 ◽  
Vol 14 (8) ◽  
pp. 5318-5325
Author(s):  
E Chuang ◽  
D Barnard ◽  
L Hettich ◽  
X F Zhang ◽  
J Avruch ◽  
...  
Keyword(s):  
Structural Changes ◽  
Regulatory Region ◽  
Ras Proteins ◽  
Binding Region ◽  
Raf Kinase ◽  
High Affinity ◽  
Critical Binding ◽  
Kinase Pathway ◽  
Zinc Finger Region

Genetic and biochemical evidence suggests that the Ras protooncogene product regulates the activation of the Raf kinase pathway, leading to the proposal that Raf is a direct mitogenic effector of activated Ras. Here we report the use of a novel competition assay to measure in vitro the relative affinity of the c-Raf-1 regulatory region for Ras-GTP, Ras-GDP, and 10 oncogenic and effector mutant Ras proteins. c-Raf-1 associates with normal Ras and the oncogenic V12 and L61 forms of Ras with equal affinity. The moderately transforming mutant Ras[E30K31] also bound to the c-Raf-1 regulatory region with normal affinity. Transformation-defective Ras effector mutants Ras[N33], Ras[S35], and Ras[N38] bound poorly. In contrast, the transformation defective Ras[G26I27] and Ras[E45] mutants bound to the c-Raf-1 regulatory region with nearly wild-type affinity. A stable, high-affinity Ras-binding region of c-Raf-1 was mapped to a 99-amino-acid subfragment of the first 257 residues. The smallest Ras-binding region identified consisted of N-terminal residues 51 to 131, although stable expression of the domain and high-affinity binding were improved by the presence of residues 132 to 149. Deletion of the Raf zinc finger region did not reduce Ras-binding affinity, while removal of the first 50 amino acids greatly increased affinity. Phosphorylation of Raf[1-149] by protein kinase A on serine 43 resulted in significant inhibiton of Ras binding. demonstrating that the mechanism of cyclic AMP downregulation results through structural changes occurring exclusively in this small Ras-binding domain.

scholarly journals Proton Triggered Colorimetric and Fluorescence Response of a Novel Quinoxaline Compromising a Donor-Acceptor System

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3433 ◽  
Author(s):  
Yogesh More ◽  
Sachin Padghan ◽  
Rajesh Bhosale ◽  
Rajendra Pawar ◽  
Avinash Puyad ◽  
...  
Keyword(s):  
Density Functional ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Paper Strip ◽  
Time Resolved ◽  
Fluorescence Studies ◽  
Color Changes ◽  
Spectral Changes ◽  
Donor Acceptor ◽  
Strip Test

Quinoxaline-based novel acid-responsive probe Q1 was designed on the basis of a conjugated donor-acceptor (D-A) subunit. Q1 shows colorimetric and fluorometric changes through protonation and deprotonation in dichloromethane. With the addition of the trifluoroacetic acid (TFA), UV-vis absorption spectral changes in peak intensity of Q1 was observed. Moreover, the appearance of a new peaks at 284 nm 434 nm in absorption spectra with the addition of TFA indicating protonation of quinoxaline nitrogen and form Q1.H+ and Q1.2H+. The emission spectra display appearance of new emission peak at 515 nm. The optical property variations were supported by time resolved fluorescence studies. The energy band gap was calculated by employing cyclic voltammetry and density functional calculations. Upon addition of triethylamine (TEA) the fluorescence emission spectral changes of Q1 are found to be reversible. Q1 shows color changes from blue to green in basic and acidic medium, respectively. The paper strip test was developed for making Q1 a colorimetric and fluorometric indicator.

scholarly journals Spectroscopic studies on lipoprotein structure modification under oxidative stress

2011 ◽  
Vol 26 (3) ◽  
pp. 167-178 ◽  
Author(s):  
Andreia Tache ◽  
Simona-Carmen Litescu ◽  
Gabriel-Lucian Radu
Keyword(s):  
Free Radicals ◽  
Metal Ion ◽  
Structural Changes ◽  
Oxidation Process ◽  
Spectroscopic Studies ◽  
Oxidative Modification ◽  
Hydroxyl Groups ◽  
Oxidative Damages ◽  
Endogenous Antioxidant

Matrix assisted laser desorption–ionization time of flight (MALDI-ToF) and infrared techniques were used to study oxidative modification of low density lipoproteins (LDL), considered to have the key role in biological process that initiates and accelerates the development of cardiovascular disease. The early identification of lipoperoxidation products creates the opportunity of the efficient prevention of eventual oxidative damages. MALDI analysis of LDL subjected toin vitrooxidation process initiated by 2,2-azobis(2-amidinopropane) dihydrochloride revealed that some fragments of lipoprotein changed the molecular weight by 16 and 32 Da due to the oxygen or hydroxyl groups attachment, and peroxide or hydroperoxide formation, while Fourier Transformed Infrared studies proved that lipoprotein changes its protein secondary conformation from predominantlyα-helix in predominantlyβ-turn. The increase in free radicals concentration correlated to structural changes, and the presence of transitional metal ion, copper (II), in the oxidation process lead to an enhancing of the damaging effects of free radicals on lipoprotein substrate. It was shown that the toxic effects of oxidants are delayed by the presence of glutathione (10 mM), an endogenous antioxidant.

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