scholarly journals Intraparticulate speciation analysis of soft nanoparticulate metal complexes. The impact of electric condensation on the binding of Cd2+/Pb2+/Cu2+by humic acids

2016 ◽  
Vol 18 (15) ◽  
pp. 10049-10058 ◽  
Author(s):  
Raewyn M. Town ◽  
Herman P. van Leeuwen
Keyword(s):  
Humic Acid ◽  
Metal Ions ◽  
Metal Complexes ◽  
Humic Acids ◽  
Speciation Analysis ◽  
The Impact

The drastic role of electrostatics in the binding of metal ions by soft charged nanoparticulate humic acid complexants is demonstrated.

scholarly journals Isolation of humic acid from oxidized lignite and complexation with metal cations

2017 ◽  
Vol 71 (4) ◽  
pp. 319-327
Author(s):  
Benjamin Catovic ◽  
Minela Sisic ◽  
Majda Srabovic ◽  
Melita Huremovic
Keyword(s):  
Humic Acid ◽  
Metal Ions ◽  
Humic Acids ◽  
Metal Binding ◽  
Base Material ◽  
Metal Cations ◽  
Biological Properties ◽  
Metal Nitrate ◽  
Chemical Difference ◽  
The Difference

Lignite is brown coal, which in its composition contains humic acids. Humic acids are produced by coal combustion, which leads to the enrichment of coal humic acids. Lignite, from the opet pit mine Sikulje, lignite ore ?Kreka?, Bosnia and Herzegovina, was fragmented and sieved to the appropriate size and used as a base material. The isolation of humic acid was carried out from pre-oxidized and dried lignite after which it was refined. Identification thus obtained humic acids was carried out by FTIR spectroscopy and its characterization of UV analysis which is determined by optical density of isolated humic acid and its complexation with metal cations. Data obtained by FTIR spectroscopic analysis of isolated humic acids show no significant structural and chemical difference in relation to the spectrum obtained for standard humic acids (Sigma Aldrich). UV analysis showed that isolated and standard humic acid have E4/E6 ratio in an appropriate range of 3?5, which indicates the presence of a large number of aliphatic structure. Based on the degree of humification was found that the isolated humic acids belong to the type B standard while humic acids belong to type A. The most important property of the humic substances is the ability to interact with the metal ions forming soluble or insoluble complexes which possess different chemical and biological properties and stability. The nature of the complex between humic acid and metal cation derived from the heterogeneous, polyelectric and polydispersive character humic acids that occurs due to the presence of a large number of functional groups. Complexation of humic acid is carried out with different concentrations of metal nitrate solutions and at different pH values. Different amounts of humic acids were used for the complexation. The amount of the free metal ions was measured with the ICP-OES methode. The data were also statistically analyzed with ANOVA. The results showed that increasing the pH reduces the concentration of metal ions adsorbed on humic acid and by increasing the concentrations and amounts of metal humic acid that power increases. On the basis of the difference in absorbance between metals and humic acids can be said that there is an interaction between the metal and the ligand and is based on absorbance values obtained can be determine the next set of metal binding to humic acids Pb>Zn>Ni>Cu.

The Effects on Angiogenesis of Relevant Inorganic Chemotherapeutics

2020 ◽  
Vol 20 ◽  
Author(s):  
Tiziano Marzo ◽  
Diego La Mendola
Keyword(s):  
Metal Ions ◽  
Anticancer Agents ◽  
Review Article ◽  
Pharmacological Effects ◽  
Complex Interactions ◽  
Pathological Conditions ◽  
Copper Zinc ◽  
Antiangiogenic Factors ◽  
The Impact

: Angiogenesis is a key process allowing the formation of blood vessels. It is crucial for all the tissue and organs, ensuring their function and growth. Angiogenesis is finely controlled by several mechanisms involving complex interactions between pro- or antiangiogenic factors and an imbalance in this control chain may result in pathological conditions. Metals as copper, zinc and iron cover an essential role in regulating angiogenesis, thus therapies having physiological metals as target have been proposed. Also, some complexes of heavier metal ions (e.g Pt, Au, Ru) are currently used as established or experimental anticancer agents targeting genomic or non-genomic targets. These molecules may affect the angiogenic mechanisms determining different effects that have been only poorly and non-systematically investigated so far. Accordingly, in this review article we aim to recapitulate the impact on the angiogenic process of some reference anticancer drugs, and how it is connected to the overall pharmacological effects. Also, we highlight how the activity of these drugs can be related to the role of biological essential metal ions. Overall, this may allow a deeper description and understanding of the antineoplastic activity of both approved or experimental metal complexes, providing important insights for the synthesis of new inorganic drugs able to overcome resistance and recurrence phenomena.

scholarly journals The effect of magnesium ions on triphosphate hydrolysis

2017 ◽  
Vol 89 (6) ◽  
pp. 715-727 ◽  
Author(s):  
Alexandre Barrozo ◽  
David Blaha-Nelson ◽  
Nicholas H. Williams ◽  
Shina C. L. Kamerlin
Keyword(s):  
Transition State ◽  
Metal Ions ◽  
Density Functional ◽  
Reaction Pathway ◽  
Enzymatic Reaction ◽  
Phosphate Ester ◽  
Mechanistic Pathway ◽  
Phosphate Hydrolysis ◽  
The Impact

AbstractThe role of metal ions in catalyzing phosphate ester hydrolysis has been the subject of much debate, both in terms of whether they change the transition state structure or mechanistic pathway. Understanding the impact of metal ions on these biologically critical reactions is central to improving our understanding of the role of metal ions in the numerous enzymes that facilitate them. In the present study, we have performed density functional theory studies of the mechanisms of methyl triphosphate and acetyl phosphate hydrolysis in aqueous solution to explore the competition between solvent- and substrate-assisted pathways, and examined the impact of Mg2+ on the energetics and transition state geometries. In both cases, we observe a clear preference for a more dissociative solvent-assisted transition state, which is not significantly changed by coordination of Mg2+. The effect of Mg2+ on the transition state geometries for the two pathways is minimal. While our calculations cannot rule out a substrate-assisted pathway as a possible solution for biological phosphate hydrolysis, they demonstrate that a significantly higher energy barrier needs to be overcome in the enzymatic reaction for this to be an energetically viable reaction pathway.

scholarly journals Molecular Features and Metal Ions That Influence 10-23 DNAzyme Activity

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 3100 ◽  
Author(s):  
Hannah Rosenbach ◽  
Julian Victor ◽  
Manuel Etzkorn ◽  
Gerhard Steger ◽  
Detlev Riesner ◽  
...  
Keyword(s):  
Metal Ions ◽  
Structure Determination ◽  
Structural Information ◽  
Pyrimidine Nucleotides ◽  
Molecular Features ◽  
Biological Studies ◽  
Catalytic Loop ◽  
The Impact

Deoxyribozymes (DNAzymes) with RNA hydrolysis activity have a tremendous potential as gene suppression agents for therapeutic applications. The most extensively studied representative is the 10-23 DNAzyme consisting of a catalytic loop and two substrate binding arms that can be designed to bind and cleave the RNA sequence of interest. The RNA substrate is cleaved between central purine and pyrimidine nucleotides. The activity of this DNAzyme in vitro is considerably higher than in vivo, which was suggested to be related to its divalent cation dependency. Understanding the mechanism of DNAzyme catalysis is hindered by the absence of structural information. Numerous biological studies, however, provide comprehensive insights into the role of particular deoxynucleotides and functional groups in DNAzymes. Here we provide an overview of the thermodynamic properties, the impact of nucleobase modifications within the catalytic loop, and the role of different metal ions in catalysis. We point out features that will be helpful in developing novel strategies for structure determination and to understand the mechanism of the 10-23 DNAzyme. Consideration of these features will enable to develop improved strategies for structure determination and to understand the mechanism of the 10-23 DNAzyme. These insights provide the basis for improving activity in cells and pave the way for developing DNAzyme applications.

scholarly journals Functionalising metal–organic frameworks with metal complexes: the role of structural dynamics

CrystEngComm ◽  
2015 ◽  
Vol 17 (40) ◽  
pp. 7632-7635 ◽  
Author(s):  
Ana E. Platero-Prats ◽  
Antonio Bermejo Gómez ◽  
Karena W. Chapman ◽  
Belén Martín-Matute ◽  
Xiaodong Zou
Keyword(s):  
Metal Complexes ◽  
Structural Dynamics ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Metal Organic ◽  
The Impact ◽  
Organic Framework

The impact of dynamics in the functionalisation of metal–organic framework UiO-67 with an Ir-complex has been studied. Highly functionalised Ir-UiO-67 can be only trapped as kinetic products, which lose metals and exchange species to gain stability.

Sign in / Sign up

Export Citation Format

Share Document