Complexes binaires et ternaires du cuivre(II) avec la 1-canavanine et la 1-arginine examinés par potentiométrie, spectrophotométrie visible et dichroïsme circulaire

1989 ◽  
Vol 67 (6) ◽  
pp. 959-966 ◽  
Author(s):  
Abdallah Albourine ◽  
Michelle Petit-Ramel ◽  
Germaine Thomas-David. ◽  
Jean-Jacques Vallon
Keyword(s):  
Amino Acids ◽  
Circular Dichroism ◽  
Visible Region ◽  
Bidentate Ligand ◽  
Ternary Complexes ◽  
Tridentate Ligand ◽  
Structural Analogue ◽  
Binary And Ternary Complexes ◽  
The Stability ◽  
Circular Dichroïsm

The protonation constants of 1 -canavanine (Can) and its structural analogue 1-arginine (Arg) have been calculated at 25 °C and at ionic strength μ = 0.1 (NaNO3). Under the same conditions, the stability constants of the binary and ternary complexes with Cu(II) have been determined by potentiometry, spectrophotometry, and by circular dichroïsm in the visible region. A comparative study of these two amino acids allows us to differentiate the order of protonation of the three functional groups (carboxylic, amino, and guanidyl), mainly by the different modes of complexation with copper(II), which is found in an octahedral coordination: arginine behaves like a bidentate ligand (glycine type) whereas canavanine behaves like a tridentate ligand. Keywords: 1-arginine, 1-canavanine, circular dichroïsm, copper ternary coordination, potentiometry.

Complexes binaires du nickel(II) et du zinc(II) avec la 1-canavanine et la 1-arginine, études potentiométriques et spectroscopiques

1991 ◽  
Vol 69 (9) ◽  
pp. 1344-1351 ◽  
Author(s):  
Abdallah Albourine ◽  
Michelle Petit-Ramel ◽  
Germaine Thomas-David ◽  
Jean Jacques Vallon
Keyword(s):  
Circular Dichroism ◽  
Ionic Strength ◽  
Key Words ◽  
Stability Constants ◽  
Bidentate Ligand ◽  
Tridentate Ligand ◽  
Key Words 1 ◽  
Binary Complexes ◽  
The Stability ◽  
Circular Dichroïsm

The stability constants of binary complexes of 1-canavanine (Can) and 1-arginine (Arg) with Ni2+ and Zn2+ have been calculated at 25 °C and at ionic strength μ = 0.1 (NaNO3). This technique is completed with spectrophotometry and circular dichroïsm measurements in the ultraviolet and visible ranges. Thus we determined the molar absorbances and the molar circular dichroïsm of ligands and complexes with Ni2+ and Zn2+. Concerning the nickel(II), these measurements display three complexes, NiL, NiL2, and NiL3. 1-Canavanine, which generally has a tridentate ligand behaviour, becomes a bidentate ligand in the Ni(Can)3 complex. With regard to zinc(II), this study only displays the ZnL and ZnL2 species. Key words: 1-arginine, 1-canavanine, circular dichroïsm, nickel binary coordination, zinc binary coordination.

Circular dichroism spectra of amino acid complexes. II. Chelated amino acid complexes with the CoN5O chromophore

1970 ◽  
Vol 23 (9) ◽  
pp. 1735 ◽  
Author(s):  
CJ Hawkins ◽  
PJ Lawson
Keyword(s):  
Amino Acids ◽  
Circular Dichroism ◽  
Amino Acid ◽  
Visible Region ◽  
Optically Active ◽  
Circular Dichroism Spectra ◽  
Amino Acid Complexes ◽  
Similar Series ◽  
Cotton Effects ◽  
Circular Dichroïsm

The circular dichroism spectra of a series of optically active (α-aminocarboxylato)tetraamminecobalt(111) complexes have been measured in aqueous solution, and in the presence of salts of polarizable anions. The observed spectra in the visible region have been analysed to determine the signs of the Cotton effects of the three components of the 1A1g ↔ 1T1g cobalt(111) transition. For L-amino acids, the transition with A2g(D4h) parentage is negative, and the two transitions with Eg(D4h) parentage have opposite signs. Published circular dichroism spectra of complexes of the type [Co(en)2(L-am)]2+ were similarly interpreted in terms of a perturbed tetragonal chromophore, and it was shown that the vicinal effect of the L-amino acids imposed the same signs onto the component transitions as for the tetraammines and for a similar series of pentaamminecobalt(111) complexes.

scholarly journals Characterization by Potentiometric Procedures of the Stability Constants of the Binary and Ternary Complexes of Cu(II) and Duloxetine Drug with Amino Acids

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Amal M. Al-Mohaimeed ◽  
Asma A. Alothman
Keyword(s):  
Amino Acids ◽  
Stability Constants ◽  
Formation Constants ◽  
Ternary Complexes ◽  
Planar Geometry ◽  
Binary And Ternary Complexes ◽  
Mass Spectral ◽  
Binary Complexes ◽  
Potentiometric Titration Method ◽  
The Stability

Potentiometric titration method has been used to define stoichiometries and stability constants of ternary complexes of Cu(II) with duloxetine (D) and some selected amino acids (L). The protonation constants of the ligands and the stability constants of the binary and ternary complexes of Cu(II) with the ligands were calculated from the potentiometric data using the HYPERQUAD program. The formation constants of the complexes formed in aqueous solutions and their concentration distributions as a function of pH were evaluated at 25°C and ionic strength 0.10 mol·L−1 NaNO3. Respective stabilities of ternary complexes have been determined compared with the corresponding binary complexes in terms of Δlog  K and %R.S. values. A novel binary and ternary duloxetine (D) drug with glycine and its Cu(II) complexes has been synthesized and characterized by several spectroscopic methods. Electronic spectra and magnetic susceptibility measurements reveal square planar geometry for both complexes. The elemental analyses and mass spectral data have justified the [Cu(D)(Gly)] and [Cu(D)Cl(H2O)] composition of complexes, where D = duloxetine and Gly = glycine. The EPR spectra of Cu(II) complexes support the mononuclear structures. Thermal properties and decomposition kinetics of Cu(II) complexes are investigated.

scholarly journals Equilibrium Study and Biological Activity of Cu(II) with Polyvinyl alcohol(PVA) and Some Amino acids and DNA

2007 ◽  
Vol 3 (3) ◽  
pp. 264-277
Author(s):  
Wafaa Hosny ◽  
Perihan Khalaf- Alaa
Keyword(s):  
Amino Acids ◽  
Polyvinyl Alcohol ◽  
Antimicrobial Activities ◽  
Ternary Complexes ◽  
Diffusion Method ◽  
Disc Diffusion Method ◽  
Binary And Ternary Complexes ◽  
Dna Constituents ◽  
Bacteria And Fungi ◽  
The Stability

This study presents the acid-base equilibrium of polyvinyl alcohol (PVA). The stability constant values of the binary and ternary complexes formed in solution among polyvinyl alcohol, Cu (II), some amino acids and DNA were determined potentiomertically. The stability constants of the complexes are determined and the concentration distribution diagrams of the complexes are evaluated. The ligand and their metal chelates have been screened for their antimicrobial activities using the disc diffusion method against the selected bacteria and fungi. Binary and ternary complexes of copper (II) involving polyvinyl alcohol (PVA) and various biologically relevant ligands containing different functional groups, were investigated. The ligands (L) are amino acids and DNA constituents. The ternary complexes of amino acids and DNA are formed by simultaneous reactions respectively. The results showed the formation of Cu (PVA) (L) complexes with amino acids and DNA. Amino acids form both Cu (PVA)(L) complexes and the corresponding protonated  Cu(PVA)(LH) and deprotonated species Cu(PVA)(LH−1). The ternary complexes of copper (II) with (PVA) and DNA are formed in a stepwise process, whereby binding of copper (II) to (PVA) is followed by ligation of the DNA components. DNA constituents form 1:1 complexes with Cu (PVA). The stability of these ternary complexes was quantitatively compared with their corresponding binary complexes in terms of the parameter ∆ log10K. The values of ∆ log10K indicate that the ternary complexes containing aromatic amino acids were significantly more stable than the complexes containing alkyl- and hydroxyl alkyl substituted amino acids. The concentration distribution of various complex species formed in solution was also evaluated as a function of pH. The antimicrobial activities using the disc diffusion method against some selected bacteria and fungi. The activity data show that the metal complexes are found to have antibacterial and antifungal activity.

Circular dichroism and infrared study of β-turn formation in repeat peptides of elastin

1987 ◽  
Vol 52 (5) ◽  
pp. 1356-1361
Author(s):  
S. Abdel Rahman ◽  
M. Elsafty ◽  
A. Hattaba
Keyword(s):  
Circular Dichroism ◽  
Solid State ◽  
Ir Spectra ◽  
Chain Length ◽  
Room Temperature ◽  
Infrared Study ◽  
Feature Characteristic ◽  
C 50 ◽  
The Stability ◽  
Circular Dichroïsm

The conformation of elastin-like peptides Boc-Ala-Pro-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM were examined in solution using circular dichroism at 30 °C, 50 °C, and 70 °C and in solid state by IR at room temperature. The studies show that the β-turn is a significant conformational feature for peptides under investigation in solution at 30 °C and 50 °C, but at 70 °C the tetra, hexa, and decapeptides show the CD feature characteristic of the β-structure while the dodecapeptide spectra show the presence of β-turn which indicates the stability of the β-turn at this chain length. The IR spectra show that in the solid state at room temperature all investigated peptides assume essentially a β-turn except the tetrapeptide which present evidence of antiparallel β-structure. The β-turn contribution in the IR spectra increases with the increase of the chain length of the peptide.

Equilibrium Studies of Binary and Ternary Complexes of Palladium(II) Involving Amino Acids

1993 ◽  
Vol 58 (5) ◽  
pp. 1103-1108 ◽  
Author(s):  
Mohamed M. Shoukry ◽  
Eman M. Shoukry
Keyword(s):  
Amino Acids ◽  
Relative Stability ◽  
Ternary Complex ◽  
Formation Constants ◽  
Ternary Complexes ◽  
Conductivity Measurements ◽  
Equilibrium Studies ◽  
Binary And Ternary Complexes ◽  
Binary Complexes

The formation constants of the binary and ternary complexes of palladium(II) with diethylenetriamine and amino acids as ligands have been determined potentiometrically at 25 °C in 0.1 M NaNO3 solution. The relative stability of each ternary complex was compared with that of the corresponding binary complexes in terms of ∆logK values. The mode of chelation was ascertained by conductivity measurements.

scholarly journals Detection of Protein-Protein Interactions in the Alkanesulfonate Monooxygenase System from Escherichia coli

2006 ◽  
Vol 188 (23) ◽  
pp. 8153-8159 ◽  
Author(s):  
Kholis Abdurachim ◽  
Holly R. Ellis
Keyword(s):  
Circular Dichroism ◽  
Protein Interactions ◽  
Visible Region ◽  
Circular Dichroism Spectroscopy ◽  
Flavin Mononucleotide ◽  
Stable Complex ◽  
Monooxygenase System ◽  
Protein Protein Interactions ◽  
Alkanesulfonate Monooxygenase ◽  
Circular Dichroïsm

ABSTRACT The two-component alkanesulfonate monooxygenase system utilizes reduced flavin as a substrate to catalyze a unique desulfonation reaction during times of sulfur starvation. The importance of protein-protein interactions in the mechanism of flavin transfer was analyzed in these studies. The results from affinity chromatography and cross-linking experiments support the formation of a stable complex between the flavin mononucleotide (FMN) reductase (SsuE) and monooxygenase (SsuD). Interactions between the two proteins do not lead to overall conformational changes in protein structure, as indicated by the results from circular dichroism spectroscopy in the far-UV region. However, subtle changes in the flavin environment of FMN-bound SsuE that occur in the presence of SsuD were identified by circular dichroism spectroscopy in the visible region. These data are supported by the results from fluorescent spectroscopy experiments, where a dissociation constant of 0.0022 ± 0.0010 μM was obtained for the binding of SsuE to SsuD. Based on these studies, the stoichiometry for protein-protein interactions is proposed to involve a 1:1 monomeric association of SsuE with SsuD.

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