scholarly journals Unravelling the mechanistic details of metal binding to mammalian metallothioneins from stoichiometric, kinetic, and binding affinity data

2018 ◽  
Vol 47 (11) ◽  
pp. 3613-3637 ◽  
Author(s):  
Judith S. Scheller ◽  
Gordon W. Irvine ◽  
Martin J. Stillman
Keyword(s):  
Binding Affinity ◽  
Metal Binding ◽  
Binding Constants ◽  
Equilibrium Binding ◽  
Mammalian Metallothioneins

Equilibrium binding constants are now readily accessible for metalation of metallothioneins.

Enhancement of Plasminogen Binding to U937 Cells and Fibrin by Complestatin

1997 ◽  
Vol 77 (01) ◽  
pp. 137-142 ◽  
Author(s):  
Kiyoshi Tachikawa ◽  
Keiji Hasurni ◽  
Akira Endo
Keyword(s):  
Binding Site ◽  
Binding Affinity ◽  
Blood Cells ◽  
Aminocaproic Acid ◽  
U937 Cells ◽  
Biochemical Basis ◽  
Equilibrium Binding ◽  
Pharmacological Stimulation ◽  
Endogenous Fibrinolysis ◽  
Stimulation Of

SummaryPlasminogen binds to endothelial and blood cells as well as to fibrin, where the zymogen is efficiently activated and protected from inhibition by α2-antiplasmin. In the present study we have found that complestatin, a peptide-like metabolite of a streptomyces, enhances binding of plasminogen to cells and fibrin. Complestatin, at concentrations ranging from 1 to 5 μM, doubled 125I-plasminogen binding to U937 cells both in the absence and presence of lipoprotein(a), a putative physiological competitor of plasminogen. The binding of 125I-plasminogen in the presence of complestatin was abolished by e-aminocaproic acid, suggesting that the lysine binding site(s) of the plasminogen molecule are involved in the binding. Equilibrium binding analyses indicated that complestatin increased the maximum binding of 125I-plasminogen to U937 cells without affecting the binding affinity. Complestatin was also effective in increasing 125I-plasminogen binding to fibrin, causing 2-fold elevation of the binding at ~1 μM. Along with the potentiation of plasminogen binding, complestatin enhanced plasmin formation, and thereby increased fibrinolysis. These results would provide a biochemical basis for a pharmacological stimulation of endogenous fibrinolysis through a promotion of plasminogen binding to cells and fibrin.

A Fluorescence Quenching Analysis of the Binding of Fluoroquinolones to Humic Acid

2017 ◽  
Vol 71 (11) ◽  
pp. 2512-2518 ◽  
Author(s):  
Ryan P. Ferrie ◽  
Gregory E. Hewitt ◽  
Bruce D. Anderson
Keyword(s):  
Humic Acid ◽  
Fluorescence Quenching ◽  
Water Solubility ◽  
Binding Constants ◽  
High Water ◽  
Static Quenching ◽  
Temperature Range ◽  
Equilibrium Binding ◽  
Quenching Analysis ◽  
High Water Solubility

Fluorescence quenching was used to investigate the interaction of six fluoroquinolones with humic acid. Static quenching was observed for the binding of ciprofloxacin, enoxacin, fleroxacin, levofloxacin, norfloxacin, and ofloxacin to humic acid. The equilibrium binding constants were found from Stern–Volmer plots of the data. The quenching experiments were repeated over a temperature range of 25–45 ℃ and van’t Hoff plots were generated. From these linear plots, thermodynamic values were calculated for Δ H, Δ G, and Δ S for each of the fluoroquinolones. The equilibrium binding constants were found to be <1 for all the antibiotics studied. The calculated ΔH values were all negative and ranged from −9.5 to −27.6 kJ/mol. The high water solubility of the antibiotics and low ΔH of binding suggests that the antibiotics will be transported easily through the environment. Finally, whether the fluoroquinolones are in a protonated, deprotonated, or partially protonated state is found to correlate to the strength of binding to humic acid.

Metal-binding hydrazone photoswitches for visible light reactivity and variable relaxation kinetics

2017 ◽  
Vol 16 (11) ◽  
pp. 1604-1612 ◽  
Author(s):  
Kacey C. Hall ◽  
Andrew T. Franks ◽  
Rory C. McAtee ◽  
Michael S. Wang ◽  
Vivian I. Lu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Visible Light ◽  
Binding Affinity ◽  
Blue Light ◽  
Metal Binding ◽  
Relaxation Kinetics ◽  
Photostationary State ◽  
State Composition

Photoactive aroylhydrazones demonstrate variability in UVA, UVC and blue light photoreactivity, photostationary state composition, photoisomer thermal stability, and relative iron(iii) binding affinity in ways that may inform metal-gated photoswitching applications.

scholarly journals Iron is a ligand of SecA-like metal-binding domains in vivo

2020 ◽  
Vol 295 (21) ◽  
pp. 7516-7528
Author(s):  
Tamar Cranford-Smith ◽  
Mohammed Jamshad ◽  
Mark Jeeves ◽  
Rachael A. Chandler ◽  
Jack Yule ◽  
...  
Keyword(s):  
Sodium Azide ◽  
Metal Binding ◽  
Cytoplasmic Membrane ◽  
E Coli ◽  
Binding Domains ◽  
Equilibrium Binding ◽  
Plausible Model ◽  
Metal Binding Domain ◽  
Linker Domain

The ATPase SecA is an essential component of the bacterial Sec machinery, which transports proteins across the cytoplasmic membrane. Most SecA proteins contain a long C-terminal tail (CTT). In Escherichia coli, the CTT contains a structurally flexible linker domain and a small metal-binding domain (MBD). The MBD coordinates zinc via a conserved cysteine-containing motif and binds to SecB and ribosomes. In this study, we screened a high-density transposon library for mutants that affect the susceptibility of E. coli to sodium azide, which inhibits SecA-mediated translocation. Results from sequencing this library suggested that mutations removing the CTT make E. coli less susceptible to sodium azide at subinhibitory concentrations. Copurification experiments suggested that the MBD binds to iron and that azide disrupts iron binding. Azide also disrupted binding of SecA to membranes. Two other E. coli proteins that contain SecA-like MBDs, YecA and YchJ, also copurified with iron, and NMR spectroscopy experiments indicated that YecA binds iron via its MBD. Competition experiments and equilibrium binding measurements indicated that the SecA MBD binds preferentially to iron and that a conserved serine is required for this specificity. Finally, structural modeling suggested a plausible model for the octahedral coordination of iron. Taken together, our results suggest that SecA-like MBDs likely bind to iron in vivo.

scholarly journals Distinctive Trend of Metal Binding Affinity via Hydration Shell Breakage in Nanoconfined Cavity

2019 ◽  
Vol 123 (23) ◽  
pp. 14825-14833 ◽  
Author(s):  
Jiancheng Luo ◽  
Songtao Ye ◽  
Tao Li ◽  
Erik Sarnello ◽  
Hui Li ◽  
...  
Keyword(s):  
Binding Affinity ◽  
Metal Binding ◽  
Hydration Shell
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