scholarly journals The Role of the Disulfide Bridge in the Copper (II) Binding by the Cyclic His4-Peptide

2021 ◽  
Vol 22 (12) ◽  
pp. 6458
Author(s):  
Aleksandra Pieniężna ◽  
Weronika Witak ◽  
Aneta Szymańska ◽  
Justyna Brasuń
Keyword(s):  
Metal Ions ◽  
Coordination Mode ◽  
Transition Metal Ions ◽  
Disulfide Bridge ◽  
Chain Flexibility ◽  
Vis Spectroscopy ◽  
Ph Range ◽  
Cd Studies ◽  
Metal Ratios

In this paper, we present studies on the influence of the disulfide bridge on the copper (II) ions’ binding abilities by the cyclic His4-peptide. The studied ligand HKHPHRHC-S-S-C consists of nine amino acids. The cyclic structure was obtained through a disulfide bridge between two cysteinyl groups. Moreover, this peptide is characterized by the presence of four His residues in the sequence, which makes it an interesting ligand for transition metal ions. The potentiometric and spectroscopic (UV-Vis spectroscopy and circular dichroism spectroscopy (CD)) studies were carried out in various molar ligand to metal ratios: 2:1, 1:1, and 1:2, in the pH range of 2.5–11 at 25 °C. The results showed that the cyclic His4-peptide promotes dinuclear complexes in each of these systems and forms the final dinuclear species with the {NIm, 3N-amide}{NIm, 3N-amide} coordination mode. The obtained data shows that cyclization by the formation of the disulfide bond has an impact on the peptide chain flexibility and appearance of additional potential donors for metal ions and influences the copper (II) ions’ coordination.

The Role of Transition Metal Ions in Ascorbate-Induced Cytotoxicity in Pancreatic Cancer

2014 ◽  
Vol 76 ◽  
pp. S124
Author(s):  
Juan Du ◽  
Brett A Wagner ◽  
Garry R Buettner ◽  
Joseph J Cullen
Keyword(s):  
Pancreatic Cancer ◽  
Transition Metal ◽  
Metal Ions ◽  
Transition Metal Ions

scholarly journals The role of transition metal ions on HO<sub>x</sub> radicals in clouds: a numerical evaluation of its impact on multiphase chemistry

2004 ◽  
Vol 4 (1) ◽  
pp. 95-110 ◽  
Author(s):  
L. Deguillaume ◽  
M. Leriche ◽  
A. Monod ◽  
N. Chaumerliac
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Aqueous Phase ◽  
Numerical Evaluation ◽  
Transition Metal Ions ◽  
Cloud Chemistry ◽  
Sensitivity Tests ◽  
Fe Speciation ◽  
Deposition Processes

Abstract. A new modelling study of the role of transition metal ions on cloud chemistry has been performed. Developments of the Model of Multiphase Cloud Chemistry (M2C2; Leriche et al., 2001) are described, including the transition metal ions reactivity emission/deposition processes and variable photolysis in the aqueous phase. The model is then applied to three summertime scenarios under urban, remote and marine conditions, described by Ervens et al. (2003). Chemical regimes in clouds are analyzed to understand the role of transition metal ions on cloud chemistry and especially, on HxOy chemistry, which consequently influences the sulphur and the VOCs chemistry in droplets. The ratio of Fe(II)/Fe(III) exhibits a diurnal variation with values in agreement with the available measurements of Fe speciation. In the urban case, sensitivity tests with and without TMI chemistry, show an enhancement of OH concentration in the aqueous phase when TMI chemistry is considered.

scholarly journals The Role of Metals in the Reaction Catalyzed by Metal-Ion-Independent Bacillary RNase

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Yulia Sokurenko ◽  
Vera Ulyanova ◽  
Pavel Zelenikhin ◽  
Alexey Kolpakov ◽  
Dmitriy Blokhin ◽  
...  
Keyword(s):  
Metal Ions ◽  
Rna Structure ◽  
Metal Ion ◽  
Extracellular Enzymes ◽  
Bacillus Pumilus ◽  
Transition Metal Ions ◽  
The Body ◽  
Intestinal Microbiome ◽  
Phosphodiester Bond

Extracellular enzymes of intestinal microbiota are the key agents that affect functional activity of the body as they directly interact with epithelial and immune cells. Several species of theBacillusgenus, likeBacillus pumilus, a common producer of extracellular RNase binase, can populate the intestinal microbiome as a colonizing organism. Without involving metal ions as cofactors, binase depolymerizes RNA by cleaving the 3′,5′-phosphodiester bond and generates 2′,3′-cyclic guanosine phosphates in the first stage of a catalytic reaction. Maintained in the reaction mixture for more than one hour, such messengers can affect the human intestinal microflora and the human body. In the present study, we found that the rate of 2′,3′-cGMP was growing in the presence of transition metals that stabilized the RNA structure. At the same time, transition metal ions only marginally reduced the amount of 2′,3′-cGMP, blocking binase recognition sites of guanine at N7 of nucleophilic purine bases.

Chemical and enzymatic characterization of recombinant rabbit muscle pyruvate kinase

2013 ◽  
Vol 394 (5) ◽  
pp. 695-701 ◽  
Author(s):  
Christian Boehme ◽  
Frank Bieber ◽  
Julia Linnemann ◽  
Reinhard Breitling ◽  
Stefan Lorkowski ◽  
...  
Keyword(s):  
Metal Ions ◽  
Pyruvate Kinase ◽  
Adenosine Diphosphate ◽  
Transition Metal Ions ◽  
Recombinant Enzyme ◽  
High Yield ◽  
Rabbit Muscle ◽  
Reading Frame ◽  
Ph Range ◽  
Muscle Pyruvate Kinase

Abstract The stepwise synthesis of thymidine triphosphate (TTP) requires a kinase for phosphorylation in the last step. Because pyruvate kinase (PK) using phosphoenolpyruvate (PEP) as substrate can regenerate adenosine triphosphate and phosphorylate thymidine diphosphate as well, we chose this enzyme for the synthesis of TTP via an enzymatic cascade reaction. The metalloenzyme PK shows pronounced promiscuity and therefore fits well to the conditions of this reaction. PK commonly used today is isolated from rabbit muscle. We cloned and expressed the respective open reading frame in Escherichia coli, purified, and characterized the His-tagged recombinant enzyme. The enzyme has an activity optimum at 37°C and in the pH range from 7.4 to 7.8. Km constants conformed well with the isolated native enzyme for adenosine diphosphate (ADP) to 0.37±0.02 mm and for PEP to 0.07±0.01 mm. The recombinant enzyme shows the following range in its substrate specificity: ADP>dADP>dGDP>dCDP>thymidine diphosphate (TDP). It allows the phosphorylation of TDP to TTP in high yield (up to 95%). The metal ions Mg2+ and K+ are necessary for full enzymatic activity. The addition of transition metal ions such as Mn2+, Cu2+, Co2+, and Ni2+ reduces activity. Storage of the enzyme at -20°C retains full activity.

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