scholarly journals An Intelligent Demethylase-Driven DNAzyme Sensor for Highly Reliable Metal Ions Imaging in Living Cells

2021 ◽  
Author(s):  
Chen Hong ◽  
Qing Wang ◽  
Yingying Chen ◽  
Yuhui Gao ◽  
Shang Jinhua ◽  
...  
Keyword(s):  
Metal Ions ◽  
Epigenetic Regulation ◽  
Metal Ion ◽  
Living Cells ◽  
Ion Sensors ◽  
Site Specific ◽  
Intracellular Imaging ◽  
Metal Ion Sensors

The accurate intracellular imaging of metal ions requires an exquisite site-specific activation of metal-ion sensors, for which the pervasive epigenetic regulation strategy supplements an ideal alternative for its orthogonal control...

scholarly journals A Single Serine Residue Determines Selectivity to Monovalent Metal Ions in Metalloregulators of the MerR Family

2015 ◽  
Vol 197 (9) ◽  
pp. 1606-1613 ◽  
Author(s):  
María M. Ibáñez ◽  
Susana K. Checa ◽  
Fernando C. Soncini
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Metal Ion ◽  
Target Genes ◽  
Divalent Metal ◽  
Serine Residue ◽  
Ion Sensors ◽  
Monovalent Metal ◽  
Divalent Metal Ion ◽  
Metal Ion Sensors

ABSTRACTMerR metalloregulators alleviate toxicity caused by an excess of metal ions, such as copper, zinc, mercury, lead, cadmium, silver, or gold, by triggering the expression of specific efflux or detoxification systems upon metal detection. The sensor protein binds the inducer metal ion by using two conserved cysteine residues at the C-terminal metal-binding loop (MBL). Divalent metal ion sensors, such as MerR and ZntR, require a third cysteine residue, located at the beginning of the dimerization (α5) helix, for metal coordination, while monovalent metal ion sensors, such as CueR and GolS, have a serine residue at this position. This serine residue was proposed to provide hydrophobic and steric restrictions to privilege the binding of monovalent metal ions. Here we show that the presence of alanine at this position does not modify the activation pattern of monovalent metal sensors. In contrast, GolS or CueR mutant sensors with a substitution of cysteine for the serine residue respond to monovalent metal ions or Hg(II) with high sensitivities. Furthermore, in a mutant deleted of the Zn(II) exporter ZntA, they also trigger the expression of their target genes in response to either Zn(II), Cd(II), Pb(II), or Co(II).IMPORTANCESpecificity in a stressor's recognition is essential for mounting an appropriate response. MerR metalloregulators trigger the expression of specific resistance systems upon detection of heavy metal ions. Two groups of these metalloregulators can be distinguished, recognizing either +1 or +2 metal ions, depending on the presence of a conserved serine in the former or a cysteine in the latter. Here we demonstrate that the serine residue in monovalent metal ion sensors excludes divalent metal ion detection, as its replacement by cysteine renders a pan-metal ion sensor. Our results indicate that the spectrum of signals detected by these sensors is determined not only by the metal-binding ligand availability but also by the metal-binding cavity flexibility.

scholarly journals Hypochlorite and superoxide radicals can act synergistically to induce fragmentation of hyaluronan and chondroitin sulphates

2004 ◽  
Vol 381 (1) ◽  
pp. 175-184 ◽  
Author(s):  
Martin D. REES ◽  
Clare L. HAWKINS ◽  
Michael J. DAVIES
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Transition Metal Ions ◽  
Chloride Ions ◽  
Superoxide Radicals ◽  
Thermal Source ◽  
Site Specific ◽  
Trace Metal Ions ◽  
Electron Reduction ◽  
Polymer Fragmentation

Activated phagocytes release the haem enzyme MPO (myeloperoxidase) and also generate superoxide radicals (O2•−), and hence H2O2, via an oxidative burst. Reaction of MPO with H2O2 in the presence of chloride ions generates HOCl (the physiological mixture of hypochlorous acid and its anion present at pH 7.4). Exposure of glycosaminoglycans to a MPO–H2O2–Cl− system or reagent HOCl generates long-lived chloramides [R-NCl-C(O)-R′] derived from the glycosamine N-acetyl functions. Decomposition of these species by transition metal ions gives polymer-derived amidyl (nitrogen-centred) radicals [R-N•-C(O)-R′], polymer-derived carbon-centred radicals and site-specific strand scission. In the present study, we have shown that exposure of glycosaminoglycan chloramides to O2•− also promotes chloramide decomposition and glycosaminoglycan fragmentation. These processes are inhibited by superoxide dismutase, metal ion chelators and the metal ion-binding protein BSA, consistent with chloramide decomposition and polymer fragmentation occurring via O2•−-dependent one-electron reduction, possibly catalysed by trace metal ions. Polymer fragmentation induced by O2•− [generated by the superoxide thermal source 1, di-(4-carboxybenzyl)hyponitrite] was demonstrated to be entirely chloramide dependent as no fragmentation occurred with the native polymers or when the chloramides were quenched by prior treatment with methionine. EPR spin-trapping experiments using 5,5-dimethyl1-pyrroline-N-oxide and 2-methyl-2-nitrosopropane have provided evidence for both O2•− and polymer-derived carbon-centred radicals as intermediates. The results obtained are consistent with a mechanism involving one-electron reduction of the chloramides to yield polymer-derived amidyl radicals, which subsequently undergo intramolecular hydrogen atom abstraction reactions to give carbon-centred radicals. The latter undergo fragmentation reactions in a site-specific manner. This synergistic damage to glycosaminoglycans induced by HOCl and O2•− may be of significance at sites of inflammation where both oxidants are generated concurrently.

Synthesis of CuxNi(1−x)O coral-like nanostructures and their application in the design of a reusable toxic heavy metal ion sensor based on an adsorption-mediated electrochemical technique

2017 ◽  
Vol 4 (1) ◽  
pp. 191-202 ◽  
Author(s):  
Sayan Dey ◽  
Sumita Santra ◽  
Anupam Midya ◽  
Prasanta Kumar Guha ◽  
Samit Kumar Ray
Keyword(s):  
Heavy Metal ◽  
Detection Limit ◽  
Metal Ion ◽  
High Selectivity ◽  
Heavy Metal Ion ◽  
Electrochemical Technique ◽  
Toxic Heavy Metal ◽  
Ion Sensors ◽  
Metal Ion Sensors ◽  
Very High

Nanostructured, Cu-doped nickel oxides serve as excellent, ultra-fast, re-usable heavy metal ion sensors with an ultra-low detection limit and very high selectivity towards toxic Cr(vi) ions.

Metal Ion Sensors Based on Immobilized Fluorogenic Ligands

2008 ◽  
pp. 63-63-15 ◽  
Author(s):  
WR Seitz ◽  
LA Saari ◽  
Z Zhujun ◽  
S Pokornicki ◽  
RD Hudson ◽  
...  
Keyword(s):  
Metal Ion ◽  
Ion Sensors ◽  
Metal Ion Sensors

Cross-sensitive rare earth metal ion sensors based on extraction systems

2008 ◽  
Vol 131 (1) ◽  
pp. 29-36 ◽  
Author(s):  
A.V. Legin ◽  
V.A. Babain ◽  
D.O. Kirsanov ◽  
O.V. Mednova
Keyword(s):  
Rare Earth ◽  
Rare Earth Metal ◽  
Metal Ion ◽  
Earth Metal ◽  
Ion Sensors ◽  
Metal Ion Sensors

Metal ion sensors for trace determination of metals in drugs and pharmaceuticals

2012 ◽  
Vol 31 (3-4) ◽  
Author(s):  
Rasiklal N. Guna ◽  
Jayant M. Vyas ◽  
Ajmeer Ramkishan ◽  
Yadvendra K. Agrawal
Keyword(s):  
Metal Ion ◽  
Trace Determination ◽  
Ion Sensors ◽  
Metal Ion Sensors

Water-Soluble Bis-triazolyl Benzochalcogendiazole Cycloadducts as Tunable Metal Ion Sensors

2013 ◽  
Vol 78 (3) ◽  
pp. 1038-1044 ◽  
Author(s):  
Jonathan J. Bryant ◽  
Benjamin D. Lindner ◽  
Uwe H. F. Bunz
Keyword(s):  
Metal Ion ◽  
Water Soluble ◽  
Ion Sensors ◽  
Metal Ion Sensors

“Crowned” Fe4S4 Clusters as Electrochemical Metal Ion Sensors

2000 ◽  
Vol 2000 (2) ◽  
pp. 253-264 ◽  
Author(s):  
Robertus J. M. Klein Gebbink ◽  
Stephen I. Klink ◽  
Martinus C. Feiters ◽  
Roeland J. M. Nolte
Keyword(s):  
Metal Ion ◽  
Ion Sensors ◽  
Metal Ion Sensors
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