scholarly journals A Pentapeptide with Tyrosine Moiety as Fluorescent Chemosensor for Selective Nanomolar-Level Detection of Copper(II) Ions

2020 ◽  
Vol 21 (3) ◽  
pp. 743 ◽  
Author(s):  
Krzysztof Żamojć ◽  
Dominik Kamrowski ◽  
Magdalena Zdrowowicz ◽  
Dariusz Wyrzykowski ◽  
Wiesław Wiczk ◽  
...  
Keyword(s):  
Metal Ion ◽  
Limit Of Detection ◽  
Fluorescence Emission ◽  
Peptide Sequence ◽  
Fluorescence Emission Spectrum ◽  
Tyrosine Residue ◽  
Metal Ion Binding ◽  
Time Resolved ◽  
Selective Ligand ◽  
Emission Quenching

Herein, we have investigated principally with the use of UV and fluorescence (steady-state and time-resolved) spectroscopy the interactions between selected pentapeptides with tyrosine residue (EYHHQ, EHYHQ, EHHQY, and KYHHE) and various metal ions (Cu2+, Mn2+, Co2+, Ni2+, Zn2+, Cr3+, Cd2+, Ag+, Pb2+, Sr2+, Ba2+, Ca2+, Mg2+, Al3+, Fe2+, and Ga3+) in order to establish the relationship between the position of a tyrosine residue in the peptide sequence and the metal ion-binding properties. Among the peptides studied, EHYHQ was evaluated as an efficient and selective ligand for developing a chemosensor for the detection of copper(II) ions. While significant fluorescence emission quenching was observed for that peptide in the presence of Cu2+ cations, other metal cations used at the same and at considerably higher concentrations caused a negligible change of the fluorescence emission spectrum, indicating a high selectivity of EHYHQ for Cu2+ ions. Under optimum conditions, fluorescence intensity was inversely proportional to the concentration of Cu2+ ions. The limit of detection of Cu2+ ions with the use of EHYHQ was determined at the level of 26.6 nM. The binding stoichiometry of the complexes of the studied peptides with Cu2+ ions was evaluated spectrophotometrically and fluorimetrically (as in the case of EHYHQ confirmed by mass spectrometry) and found to be 1:2 (Cu2+-peptide) for all the investigated systems. Furthermore, the stability constant (K) values of these complexes were determined. The reversibility of the proposed Cu2+ ions sensor was confirmed, the pH range where the sensor acts was determined, while its analytical performance was compared with some other reported recently fluorescent sensors. The mechanism of the interactions between EHYHQ and Cu2+ was proposed on the basis of NMR spectroscopy investigations.

scholarly journals Analysis of the HindIII-catalyzed reaction by time-resolved crystallography

2015 ◽  
Vol 71 (2) ◽  
pp. 256-265 ◽  
Author(s):  
Takashi Kawamura ◽  
Tomoki Kobayashi ◽  
Nobuhisa Watanabe
Keyword(s):  
Electron Density ◽  
Active Site ◽  
Dna Cleavage ◽  
Metal Ion ◽  
Manganese Ions ◽  
Metal Ion Binding ◽  
Time Resolved ◽  
Manganese Ion ◽  
Ion Binding Sites ◽  
Metal Ion Binding Sites

In order to investigate the mechanism of the reaction catalyzed by HindIII, structures of HindIII–DNA complexes with varying durations of soaking time in cryoprotectant buffer containing manganese ions were determined by the freeze-trap method. In the crystal structures of the complexes obtained after soaking for a longer duration, two manganese ions, indicated by relatively higher electron density, are clearly observed at the two metal ion-binding sites in the active site of HindIII. The increase in the electron density of the two metal-ion peaks followed distinct pathways with increasing soaking times, suggesting variation in the binding rate constant for the two metal sites. DNA cleavage is observed when the second manganese ion appears, suggesting that HindIII uses the two-metal-ion mechanism, or alternatively that its reactivity is enhanced by the binding of the second metal ion. In addition, conformational change in a loop near the active site accompanies the catalytic reaction.

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.

Investigation of optical and electrochemical properties as well as metal ion sensitivities of different number of crown ether appended phthalocyanines

2013 ◽  
Vol 17 (08n09) ◽  
pp. 682-690 ◽  
Author(s):  
Sevinc Z. Topal ◽  
Devrim Atilla ◽  
Kadriye Ertekin ◽  
Jean B. Tommasino ◽  
Dominique Luneau ◽  
...  
Keyword(s):  
Crown Ether ◽  
Metal Ion ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Zinc Phthalocyanine ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Binding Properties ◽  
Fluorescence Emission Spectra

We report herein, the synthesis, and spectral and electrochemical characterization of a series of phthalocyaninato zinc complexes where two biomedically potential structures; crown ether and phthalocyanine moities were gathered on the same molecule. The effect of number of crown ether moieties on metal ion binding properties, as well as proton sensitivity were investigated by using electronic absorption and fluorescence emission spectra. Spectral behaviors of the zinc phthalocyanine complexes fused with one crown ether; Zn [ Pc (15 C 5)( C 6 H 13)6] and four crown ether; Zn [ Pc (15 C 5)4] in presence of Na + and K + ions were investigated into detail because of host-guest interactions of subjective ions with crown ether moieties, and compared with the crown ether free phthalocyanine; Zn [ Pc ( C 6 H 13)8].

scholarly journals Improvements to a laser-induced fluorescence instrument for measuring SO<sub>2</sub> – impact on accuracy and precision

2021 ◽  
Vol 14 (3) ◽  
pp. 2429-2439
Author(s):  
Pamela S. Rickly ◽  
Lu Xu ◽  
John D. Crounse ◽  
Paul O. Wennberg ◽  
Andrew W. Rollins
Keyword(s):  
Limit Of Detection ◽  
Laser System ◽  
Fluorescence Emission ◽  
Laser Induced Fluorescence ◽  
Fluorescence Signal ◽  
Fluorescence Emission Spectrum ◽  
Signal Ratio ◽  
Accuracy And Precision ◽  
Aromatic Species

Abstract. This work describes key improvements made to the in situ laser-induced fluorescence instrument for measuring sulfur dioxide (SO2) that was originally described by Rollins et al. (2016). Here, we report measurements of the SO2 fluorescence emission spectrum. These measurements allow for the determination of the most appropriate bandpass filters to optimize the fluorescence signal, while reducing the instrumental background. Because many aromatic species fluoresce in the same spectral region as SO2, fluorescence spectra were also measured for naphthalene and anisole to determine if ambient SO2 measurements could be biased in the presence of such species. Improvement in the laser system resulted in better tunability, and a significant reduction in the 216.9 nm laser linewidth. This increases the online/offline signal ratio which, in turn, improves the precision and specificity of the measurement. The effects of these improvements on the instrumental sensitivity were determined by analyzing the signal and background of the instrument, using varying optical bandpass filter ranges and cell pressures and calculating the resulting limit of detection. As a result, we report an improvement to the instrumental sensitivity by as much as 50 %.

scholarly journals Rhodamine-Triazole Functionalized Fe3O4@SiO2 Nanoparticles as Fluorescent Sensors for Heavy Metal Ions

2019 ◽  
Vol 35 (3) ◽  
pp. 1054-1061 ◽  
Author(s):  
Kanokorn Wechakorn ◽  
Pairsunan Chanpanich ◽  
Pimfa Kamkalong ◽  
Suranan Anantachisilp
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Heavy Metal Ions ◽  
Fluorescence Emission ◽  
Sio2 Nanoparticles ◽  
Fluorescent Sensors ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Color Changes

Rhodamine-triazole sensor functionalized Fe3O4@SiO2 nanoparticles were developed for the detection of heavy metal ions, namely Cu2+, Ni2+, Hg2+, Co2+, Fe3+, and Pb2+. Rhodamine conjugated with a triazole moiety (RBT) was utilized as the metal ion binding site. The RBT-Fe3O4@SiO2 nanoparticles were fully characterized by XRD, FTIR, TGA, SEM and TEM techniques. Additionally, RBT-functionalized Fe3O4@SiO2 nanoparticles can be separated from the aqueous phase by application of an external magnet, leading to clear naked-eye observation of the color changes and fluorescence enhancement. From UV-Vis absorption spectra, aqueous solutions of RBT-Fe3O4@SiO2 in the presence of heavy metal ions show an absorption peak at 554 nm. Fluorescence titration experiments reveal that the intensity of the fluorescence emission band at 574 nm is linearly dependent on Cu2+ concentration, over a 100-800 µM range. Furthermore, complexation of Cu2+ by RBT-Fe3O4@SiO2 nanoparticles can induce ring-opening of the rhodamine spirolactam ring followed by hydrolysis, confirmed by mass spectrometry.

scholarly journals Improvements to a laser-induced fluorescence instrument for measuring SO<sub>2</sub>: impact on accuracy and precision

2020 ◽  
Author(s):  
Pamela S. Rickly ◽  
Lu Xu ◽  
John D. Crounse ◽  
Paul O. Wennberg ◽  
Andrew W. Rollins
Keyword(s):  
Limit Of Detection ◽  
Fluorescence Emission ◽  
Laser Induced Fluorescence ◽  
Fluorescence Signal ◽  
Fluorescence Emission Spectrum ◽  
Signal Ratio ◽  
Accuracy And Precision ◽  
Aromatic Species

Abstract. This work describes improvements made to the in-situ laser induced fluorescence SO2 instrument as originally described in Rollins et al. (2016). We report measurements of the SO2 fluorescence emission spectrum. These measurements allow for the determination of the most appropriate bandpass filters to optimize the fluorescence signal while reducing the instrumental background. Because many aromatic species fluoresce in the same spectral region as SO2, fluorescence spectra were also measured for naphthalene and anisole to determine if ambient SO2 measurements may be biased in the presence of such species. In addition, the 216.9 nm laser linewidth was decreased in order to increase the online/offline signal ratio which in-turn increases the precision of the measurement. The effects of these improvements on the instrumental sensitivity were determined by analyzing the signal and background of the instrument using varying optical bandpass filter ranges and cell pressures and calculating the resulting limit of detection. As a result, we report an improvement to the instrumental sensitivity by as much as 50 %.

scholarly journals Tyrosine modification enhances metal-ion binding

2008 ◽  
Vol 416 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Graham S. Baldwin ◽  
Michael F. Bailey ◽  
B. Philip Shehan ◽  
Ioulia Sims ◽  
Raymond S. Norton
Keyword(s):  
Metal Ion ◽  
Fluorescence Emission ◽  
Intrinsic Property ◽  
Peptide Hormone ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Tyrosine Sulfation ◽  
Tyrosine Residues ◽  
Tyrosine Modification ◽  
Subsequent Addition

Tyrosine sulfation is a common modification of many proteins, and the ability to phosphorylate tyrosine residues is an intrinsic property of many growth-factor receptors. In the present study, we have utilized the peptide hormone CCK8 (cholecystokinin), which occurs naturally in both sulfated and unsulfated forms, as a model to investigate the effect of tyrosine modification on metal-ion binding. The changes in absorbance and fluorescence emission on Fe3+ binding indicated that tyrosine sulfation or phosphorylation increased the stoichiometry from 1 to 2, without greatly affecting the affinity (0.6–2.8 μM at pH 6.5). Measurement of Ca2+ binding with a Ca2+-selective electrode revealed that phosphorylated CCK8 bound two Ca2+ ions. CCK8 and sulfated CCK8 each bound only one Ca2+ ion with lower affinity. Binding of Ca2+, Zn2+ or Bi3+ to phosphorylated CCK8 did not cause any change in absorbance, but substantially increased the change in absorbance on subsequent addition of Fe3+. The results of the present study demonstrate that tyrosine modification may increase the affinity of metal-ion binding to peptides, and imply that metal ions may directly regulate many signalling pathways.

Photophysical Characterisation, Metal Ion Binding and Enantiomeric Recognition of Chiral Ligands Containing Phenazine Fluorophore

2004 ◽  
Vol 69 (4) ◽  
pp. 885-896 ◽  
Author(s):  
Luisa Stella Dolci ◽  
Péter Huszthy ◽  
Erika Samu ◽  
Marco Montalti ◽  
Luca Prodi ◽  
...  
Keyword(s):  
Metal Ion ◽  
Photophysical Properties ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Ammonium Ions ◽  
Enantiomerically Pure ◽  
Binding Process ◽  
High Affinity ◽  
Enantiomeric Recognition ◽  
Chiral Species

Enantiomerically pure dimethyl- and diisobutyl-substituted phenazino-18-crown-6 ligands bind metal and ammonium ions and also primary aralkylammonium perchlorates in acetonitrile with high affinity, causing pronounced changes in their luminescence properties. In addition, they show enantioselectivity towards chiral primary aralkylammonium perchlorates. The possibility to monitor the binding process by photoluminescence spectroscopy can gain ground for the design of very efficient enantioselective chemosensors for chiral species. The observed changes in the photophysical properties are also an important tool for understanding the interactions present in the adduct.

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