scholarly journals A Comparative Study on Nickel Binding to Hpn-like Polypeptides from Two Helicobacter pylori Strains

2021 ◽  
Vol 22 (24) ◽  
pp. 13210
Author(s):  
Danuta Witkowska ◽  
Agnieszka Szebesczyk ◽  
Joanna Wątły ◽  
Michał Braczkowski ◽  
Magdalena Rowińska-Żyrek
Keyword(s):  
Helicobacter Pylori ◽  
Comparative Study ◽  
Potentiometric Titration ◽  
Isothermal Titration Calorimetry ◽  
Titration Calorimetry ◽  
Binding Properties ◽  
Protein Fragments ◽  
Nickel Binding ◽  
Independent Reaction

Combined potentiometric titration and isothermal titration calorimetry (ITC) methods were used to study the interactions of nickel(II) ions with the N-terminal fragments and histidine-rich fragments of Hpn-like protein from two Helicobacter pylori strains (11637 and 26695). The ITC measurements were performed at various temperatures and buffers in order to extract proton-independent reaction enthalpies of nickel binding to each of the studied protein fragments. We bring up the problem of ITC results of nickel binding to the Hpn-like protein being not always compatible with those from potentiometry and MS regarding the stoichiometry and affinity. The roles of the ATCUN motif and multiple His and Gln residues in Ni(II) binding are discussed. The results provided the possibility to compare the Ni(II) binding properties between N-terminal and histidine-rich part of Hpn-like protein and between N-terminal parts of two Hpn-like strains, which differ mainly in the number of glutamine residues.

scholarly journals Formation of nanoparticles by cooperative inclusion between (S)-camptothecin-modified dextrans and β-cyclodextrin polymers

2015 ◽  
Vol 11 ◽  
pp. 147-154 ◽  
Author(s):  
Thorbjørn Terndrup Nielsen ◽  
Catherine Amiel ◽  
Laurent Duroux ◽  
Kim Lambertsen Larsen ◽  
Lars Wagner Städe ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Fluorescence Spectroscopy ◽  
Isothermal Titration Calorimetry ◽  
Degree Of Substitution ◽  
Titration Calorimetry ◽  
Binding Properties ◽  
High Binding ◽  
Cyclodextrin Polymers

Novel (S)-camptothecin–dextran polymers were obtained by “click” grafting of azide-modified (S)-camptothecin and alkyne-modified dextrans. Two series based on 10 kDa and 70 kDa dextrans were prepared with a degree of substitution of (S)-camptothecin between 3.1 and 10.2%. The binding properties with β-cyclodextrin and β-cyclodextrin polymers were measured by isothermal titration calorimetry and fluorescence spectroscopy, showing no binding with β-cyclodextrin but high binding with β-cyclodextrin polymers. In aqueous solution nanoparticles were formed from association between the (S)-camptothecin–dextran polymers and the β-cyclodextrin polymers.

scholarly journals Nickel binding properties of Helicobacter pylori UreF, an accessory protein in the nickel-based activation of urease

2013 ◽  
Vol 19 (3) ◽  
pp. 319-334 ◽  
Author(s):  
Barbara Zambelli ◽  
Andrea Berardi ◽  
Vlad Martin-Diaconescu ◽  
Luca Mazzei ◽  
Francesco Musiani ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Accessory Protein ◽  
Binding Properties ◽  
Nickel Binding

scholarly journals Substrate binding properties of potato tuber ADP-glucose pyrophosphorylase as determined by isothermal titration calorimetry

FEBS Letters ◽  
2015 ◽  
Vol 589 (13) ◽  
pp. 1444-1449 ◽  
Author(s):  
Bilal Cakir ◽  
Aytug Tuncel ◽  
Abigail R. Green ◽  
Kaan Koper ◽  
Seon-Kap Hwang ◽  
...  
Keyword(s):  
Potato Tuber ◽  
Isothermal Titration Calorimetry ◽  
Substrate Binding ◽  
Titration Calorimetry ◽  
Binding Properties ◽  
Adp Glucose Pyrophosphorylase

scholarly journals Helicobacter pylori UreE, a urease accessory protein: specific Ni2+- and Zn2+-binding properties and interaction with its cognate UreG

2009 ◽  
Vol 422 (1) ◽  
pp. 91-100 ◽  
Author(s):  
Matteo Bellucci ◽  
Barbara Zambelli ◽  
Francesco Musiani ◽  
Paola Turano ◽  
Stefano Ciurli
Keyword(s):  
Helicobacter Pylori ◽  
Light Scattering ◽  
Metal Ion ◽  
Site Directed Mutagenesis ◽  
Size Exclusion ◽  
Titration Calorimetry ◽  
Directed Mutagenesis ◽  
Accessory Protein ◽  
Oligomeric State ◽  
Binding Properties

The persistence of Helicobacter pylori in the hostile environment of the human stomach is ensured by the activity of urease. The essentiality of Ni2+ for this enzyme demands proper intracellular trafficking of this metal ion. The metallo-chaperone UreE promotes Ni2+ insertion into the apo-enzyme in the last step of urease maturation while facilitating concomitant GTP hydrolysis. The present study focuses on the metal-binding properties of HpUreE (Helicobacter pylori UreE) and its interaction with the related accessory protein HpUreG, a GTPase involved in the assembly of the urease active site. ITC (isothermal titration calorimetry) showed that HpUreE binds one equivalent of Ni2+ (Kd=0.15 μM) or Zn2+ (Kd=0.49 μM) per dimer, without modification of the protein oligomeric state, as indicated by light scattering. Different ligand environments for Zn2+ and Ni2+, which involve crucial histidine residues, were revealed by site-directed mutagenesis, suggesting a mechanism for discriminating metal-ion-specific binding. The formation of a HpUreE–HpUreG protein complex was revealed by NMR spectroscopy, and the thermodynamics of this interaction were established using ITC. A role for Zn2+, and not for Ni2+, in the stabilization of this complex was demonstrated using size-exclusion chromatography, light scattering, and ITC experiments. A calculated viable structure for the complex suggested the presence of a novel binding site for Zn2+, actually detected using ITC and site-directed mutagenesis. The results are discussed in relation to available evidence of a UreE–UreG functional interaction in vivo. A possible role for Zn2+ in the Ni2+-dependent urease system is envisaged.

scholarly journals Binding of urate and caffeine to haemocyanin analysed by isothermal titration calorimetry

2001 ◽  
Vol 204 (5) ◽  
pp. 1033-1038 ◽  
Author(s):  
M. Menze ◽  
N. Hellmann ◽  
H. Decker ◽  
M. Grieshaber
Keyword(s):  
Isothermal Titration Calorimetry ◽  
Equilibrium Dialysis ◽  
Oxygen Carrier ◽  
Titration Calorimetry ◽  
Oxygen Binding ◽  
Binding Properties ◽  
Induced Changes ◽  
Insight Into ◽  
Effector Binding ◽  
Binding Behaviour

Haemocyanin serves as an oxygen carrier in the haemolymph of decapod crustaceans. The oxygen-binding behaviour of the pigment is modulated by the two major anaerobic metabolites, l-lactate and urate. The binding of these two metabolites to haemocyanin has been investigated mainly indirectly by following the effector-induced changes in the oxygen-binding properties of the respiratory pigment. Only a few direct investigations of effector binding, employing ultracentrifugation techniques and equilibrium dialysis, have been carried out. No evidence for cooperative binding for either effector was detected using these methods. However, isothermal titration calorimetry (ITC) offers a useful tool to gain additional insight into the binding of effectors to these highly allosterically regulated macromolecules. By applying the ITC method to the fully oxygenated dodecameric haemocyanin of the lobster Homarus vulgaris, cooperativity in binding has been found for the urate analogue caffeine but not for urate itself: using urate and the urate analogue caffeine as ligands, two conformations of the oxygenated pigment were detected.

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