scholarly journals Inhibition of enzymes by metal ion-chelating reagents. Theory and new graphical methods of study

1974 ◽  
Vol 137 (1) ◽  
pp. 55-60 ◽  
Author(s):  
William G. Bardsley ◽  
Robert E. Childs
Keyword(s):  
Stability Constant ◽  
Metal Ions ◽  
Metal Ion ◽  
Graphical Methods ◽  
Ligand Interaction ◽  
Mechanism Of Inhibition ◽  
The Stability ◽  
Chelating Reagents

1. The mechanism of inhibition of enzymes by metal ion-chelating reagents is discussed and equations derived. 2. Two distinct mechanisms are postulated and graphical methods are given for differentiating between them. 3. Where the metal ion is actually removed from the enzyme to form a co-ordination complex in solution, a procedure is described for obtaining the stability constant for metal–enzyme interaction, the number of metal ions involved and the stoicheiometry of metal ion–ligand interaction.

scholarly journals Azocalix[4]arene with three distal ethyl ester residues as a highly selective chromogenic sensor for Ca2+ ions

2018 ◽  
Vol 24 (3) ◽  
pp. 147-150
Author(s):  
Jie Wang ◽  
Hongyu Guan ◽  
Chunhua Ge ◽  
Ping Fan ◽  
Xijuan Xing ◽  
...  
Keyword(s):  
Stability Constant ◽  
Metal Ions ◽  
Ethyl Ester ◽  
Metal Ion ◽  
Visible Spectroscopy ◽  
Binding Properties ◽  
Metal Ion Complexation ◽  
Specific Selectivity ◽  
Uv Visible ◽  
The Stability

AbstractThree azocalix[4]arenes with distal ethyl ester residues, 5-phenylazo-25,26,27-tris[(ethoxycarbonyl)methoxy]-28-hydroxycalix[4]arene (2), 5-(o-methylphenyl)azo-25,26,27-tris[(ethoxycarbonyl)methoxy]-28-hydroxycalix[4]arene (3), 5-(p-Methylphenyl)azo-25,26,27-tris[(ethoxycarbonyl)methoxy]-28-hydroxycalix[4]arene (4), were synthesized and their binding properties with metal ions were investigated by ultraviolet (UV)/visible spectroscopy. The chromogenic behavior of these compounds upon metal ion complexation indicates a specific selectivity toward Ca2+ ion in the presence of other cations tested. The stoichiometry of 3 to Ca2+ ion in the complex is 1:1 and the stability constant of the complex is 1.28×104m−1.

Transferrin binding of Al3+ and Fe3+.

1987 ◽  
Vol 33 (3) ◽  
pp. 405-407 ◽  
Author(s):  
R B Martin ◽  
J Savory ◽  
S Brown ◽  
R L Bertholf ◽  
M R Wills
Keyword(s):  
Stability Constant ◽  
Blood Plasma ◽  
Stability Constants ◽  
Metal Ion ◽  
Equilibrium Dialysis ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Quantitative Studies ◽  
Intensity Changes ◽  
The Stability

Abstract An understanding of Al3+-induced diseases requires identification of the blood carrier of Al3+ to the tissues where Al3+ exerts a toxic action. Quantitative studies demonstrate that the protein transferrin (iron-free) is the strongest Al3+ binder in blood plasma. Under plasma conditions of pH 7.4 and [HCO3-]27 mmol/L, the successive stability constant values for Al3+ binding to transferrin are log K1 = 12.9 and log K2 = 12.3. When the concentration of total Al3+ in plasma is 1 mumol/L, the free Al3+ concentration permitted by transferrin is 10(-14.6) mol/L, less than that allowed by insoluble Al(OH)3, by Al(OH)2H2PO4, or by complexing with citrate. Thus transferrin is the ultimate carrier of Al3+ in the blood. We also used intensity changes produced by metal ion binding to determine the stability constants for Fe3+ binding to transferrin: log K1 = 22.7 and log K2 = 22.1. These constants agree closely with a revision of the reported values obtained by equilibrium dialysis. By comparison with Fe3+ binding, the Al3+ stability constants are weaker than expected; this suggests that the significantly smaller Al3+ ions cannot coordinate to all the transferrin donor atoms available to Fe3+.

scholarly journals Design and Development of Complexation of Ce+3 Metal Ions with Synthesized INZ Incorporated Bio-active Schiff Bases

2021 ◽  
Vol 11 (4) ◽  
pp. 3989-4006
Keyword(s):  
Schiff Base ◽  
Metal Ions ◽  
Schiff Bases ◽  
Elemental Analysis ◽  
Metal Ion ◽  
Organic Ligands ◽  
Schiff Base Complexes ◽  
Spectral Techniques ◽  
The Stability ◽  
Antibacterial And Antifungal

In the present research, a series of Ce+3 metal ions complexation with INZ incorporating Schiff bases have been reported. INZ incorporated Schiff Bases (3a-e) were developed by condensing INZ with substituted aromatic aldehyde and confirmed with various spectral Techniques such as Elemental analysis, UV, IR, 1H-NMR, 13H NMR. All the synthesized organic ligands were evaluated against antibacterial and antifungal stains and found moderate to significant results. The Ce+3 metal ion solution mixed with newly prepared bio-active INZ Schiff bases (3a-e) to afford the [Ce-INZ Schiff Base] complexes (4a-e). The stability constants of prepared complexes were evaluated and found in order as a (3e) > (3d) > (3a) > (3b) > (3c).

METAL ION-LIGAND INTERACTION: HSAB PRINCIPLE VERSUS NBO AND AIM VIEW POINTS

2006 ◽  
Vol 05 (01) ◽  
pp. 87-98 ◽  
Author(s):  
AFSHAN MOHAJERI ◽  
MARYAM ABASI
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Hard Metal ◽  
Quantitative Model ◽  
Interaction Energies ◽  
Ligand Interaction ◽  
Hsab Principle ◽  
Soft Metal ◽  
Aim And Nbo ◽  
Soft Acid

Ab initio calculations were performed to study the applicability and reliability of the semi quantitative model based on the local hard-soft acid-base principle in studying the interaction of metal ions with ligands. The particular attention is devoted to the interaction of CO , CN - and SCN - as the base with some hard metal ions ( Li +, Na +, K +) and some soft metal ions ( Pd +2, Ag +2, Cd +2) as acids. The interaction energies were calculated using the HSAB principle and compared with the values obtained by the conventional MP2 method. The results show that the HSAB principle does not work in many cases and it fails to predict correct values for interaction energies. The AIM and NBO analyses were also performed to characterize the nature of the metal ion-ligand interaction. It is found that the charge transfers have great significance in the interaction of metal ions with ligands.

Complexation of Alkali Metal Ions by the Cryptand 4,7,13,16-Tetraoxa-1,10-diazabicyclo[8.8.5]tricosane in Several Solvents

1994 ◽  
Vol 47 (1) ◽  
pp. 123 ◽  
Author(s):  
R Dhillon ◽  
SF Lincoln
Keyword(s):  
Stability Constant ◽  
Alkali Metal ◽  
Metal Ions ◽  
Potentiometric Titration ◽  
Propylene Carbonate ◽  
Alkali Metal Ions ◽  
Factors Affecting ◽  
The Stability ◽  
Titration Study ◽  
Complexation Process

A potentiometric titration study of the complexation of metal ions (M+) by 4,7,13,16- tetraoxa-1,10-diazabicyclo[8.8.5] tricosane (C22C5) at 298.2 K and I = 0.05 (NEt4ClO4) yields log(K/dm3 mol-1) =6.07 and 5.36, 7.55 and 5.95, 6.26 and 7.56, 5.5 and 6.66, 4.57 and 5.16, and 8.14 and 14.51 when M+ = Li+, Na+, K+, Rb +, Cs+ and Ag+, respectively, where the first and second magnitudes of each pair refer to the stability constant (K) for [M(C22C5)]+ in acetonitrile and ropylene carbonate solvent, respectively. A 7Li n.m.r. tudy yields kd (298.2 K) = 428 s-1, ∆ Hd ‡ = 24.7 kJ mol-1 and ∆ Sd ‡ = -111 J K-1 mol-1 for the monomolecular decomplexation of Li+ from [Li(C22C5)]+, and kc(298.2 K) = 9.83×107 dm3 mol-1 s-1 for the complexation process in propylene carbonate. These data are compared with those for related systems and are discussed in terms of the factors affecting cryptate stability and lability.

scholarly journals Comparative study of binding strengths of heavy metals with humic acid

2013 ◽  
Vol 67 (5) ◽  
pp. 773-779 ◽  
Author(s):  
Ivana Kostic ◽  
Tatjana Andjelkovic ◽  
Ruzica Nikolic ◽  
Tatjana Cvetkovic ◽  
Dusica Pavlovic ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Humic Acid ◽  
Metal Ions ◽  
Stability Constants ◽  
Metal Ion ◽  
Heavy Metal Ions ◽  
Exchange Method ◽  
Divalent Metal Ion ◽  
The Stability

The complexation of humic acid with certain heavy metal ions (Co(II), Ni(II), Cu(II), Zn(II) and Pb(II)) was investigated. The stability constants of humate complexes were determined by method which is based on distribution of metal ions between solution and resin in the presence and the absence of ligand, known as Schubert?s ion exchange method. Experiments were performed at 25 ?C, at pH 4.0 and ionic strength of 0.01 mol dm-3. It was found that the 1:1 complexes were formed between metal ions and humic acid. Obtained results of the stability constants, log ?mn, of complexes formed between the metal ions and humic acid follow the order Co(II) < Ni(II) < Cu(II) > Zn(II) which is the same like in the Irving-Williams series for the binding strength of divalent metal ion complexes. Stability constant of complex between Pb(II) ions and humic acid is greater than stability constants of other investigated metal-humate complexes. The investigation of interaction between heavy metal ions and humics is important for the prediction of the distribution and control of the migration of heavy metals in natural environment.

scholarly journals Density Functional Theory Analysis of Poly Glycolic Acid with Metal Ions (Na+, K+) Interaction

2019 ◽  
Vol 9 (1S3) ◽  
pp. 366-369
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Density Functional ◽  
Glycolic Acid ◽  
Carbonyl Oxygen ◽  
Chemical Hardness ◽  
Binding Affinities ◽  
Functional Theory ◽  
Fukui Functions ◽  
The Stability

The complexation between Poly glycolic acid (PGA) and alkali metal ions (Na+ , K+ ) have been studied using B3LYP/6-311++G** method. The binding site of metal ion interaction on PGA is carbonyl oxygen. Both metal ions form bidendate complexation with PGA. Further, it can be noted that the PGA with K+ complex is more stable than the PGA with Na+ complex. The binding affinities (ΔH), basicity (ΔG) and the complexation entropies (ΔS) of all the studied systems are calculated. The interaction energy is maximum in PGA-Na+ than the PGA-K + complex. This is due to more charge transfer taking place between PGA and Na. The stability of the complex is studied by the chemical hardness value. The condensed Fukui functions are calculated and are used to predict the favourable reactive site

scholarly journals Nano Synthesis and Characterization of Complex Derived from Silver Metal Conjugated with Midodrine Hydrochloride

2021 ◽  
Vol 37 (1) ◽  
pp. 157-161
Author(s):  
Namita Bharadwaj ◽  
Jaishri Kaushik
Keyword(s):  
Stability Constant ◽  
Silver Nanoparticle ◽  
Metal Ion ◽  
Ratio Method ◽  
Synthesis And Characterization ◽  
Face Centered Cubic ◽  
Uv Visible ◽  
Face Centered ◽  
The Stability

The stability constant Kf for the complexation of Ag(Ⅰ) metal ion with Midodrine hydrochloride were determinedby spectrophotometric method at room temperature .The colored complexes were measured at 300 nm. The stability constant of the complexes were found to be 5.47 by mole ratio method. The stoichiometry of the complexes formed between the Midodrine drug and Ag (Ⅰ) metal ion are 1:1 M/L ratio. Silver conjugated Midodrine hydrochloride Nano synthesized and characterized by UV/Visible spectroscopy, SEM, XRD and FT-IR. The UV/Visible spectra of Midodrine –Ag nanoparticle in the range of 322 nm. XRD conformThe crystallite size of Midodrine - Ag (Ⅰ) nanoparticles are found to be 64.5 nmfrom Debye Scherer formula.Thecrystallinity of nanoparticles is Face centered cubic structure. SEM conform of particle size and surface morphology, FTIR analyzed involvement of -NH2 group in Midodrine is the stabilized of silver nanoparticle. This research is focuses on complexation, Nano synthesis and characterization of Drug-silver nanoparticle for antihypotention therapy.

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