An ESR study of the copper(II)-glycyl-L-serine and copper(II)-L-seryl-glycine systems by the simultaneous analysis of multi-component isotropic spectra. Formation constants and coordination modes

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Abstract

The formation constants and the isotropic ESR parameters (g-factors, 63Cu, 65Cu, 14N hyperfine coupling constants and relaxation parameters) of the various species were determined by the simultaneous analysis of a series of spectra, taken in a circulating system at various pH and ligand-to-metal concentration ratio. For both systems the new [CuLH]2+ complex was identified in acidic solutions. With the glycyl-L-serine ligand below pH 11.5 the same complexes and coordination modes are formed than with simple dipeptides. The side-chain donor group is bound only over pH 11.5 in the complex [CuLH-2(OH)]2-, where it is deprotonated and substitutes the carboxylate O in the third equatorial site. For the bis complex [CuLH-1(L)] - an isomeric equilibrium was shown, where the difference between the isomers was based on which of the donor atoms of the 'L' ligand, the peptide O or the amino N, occupies the fourth equatorial position, and which one is coordinated axially. The L-seryl-glycine ligand forms the same species as simple dipeptides and glycyl-L-serine up to pH 8. The only difference is that the axial binding of the alcoholic OH group fairly stabilizes the bidentate equatorial coordination of the 'L' ligand through the amino N and peptide O atoms in the [CuL]+ complex as well as in the major isomer of the [CuLH-1(L)]- complex. For this system we showed that (1) proton loss and the equatorial coordination of the alcoholic OH group occurs at relatively low pH (over pH 8-9), which results in the [CuL2H-2]2- complex with excess ligand, and also the newly identified species [Cu2L2H-4]2-: (2) this process is in competition with the proton loss of a coordinated water molecule. For both systems, the ESR-inactive species [Cu2L2H-3]- was also shown.

Original languageEnglish
Pages (from-to)995-1003
Number of pages9
JournalPolyhedron
Volume20
Issue number9-10
DOIs
Publication statusPublished - Apr 30 2001

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glycine
Glycine
Paramagnetic resonance
Amino acids
Copper
Ligands
copper
ligands
Dipeptides
Isomers
Serine
Peptides
peptides
Protons
isomers
Atoms
protons
Coordination Complexes
carboxylates
atoms

Keywords

  • Coordination modes
  • Copper(II) complexes
  • ESR
  • Formation constants
  • Glycyl-L-serine
  • Isomerism
  • L-Seryl-glycine

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry
  • Physical and Theoretical Chemistry
  • Materials Chemistry

Cite this

@article{1b4ed28582484ac8817fbd719730694f,
title = "An ESR study of the copper(II)-glycyl-L-serine and copper(II)-L-seryl-glycine systems by the simultaneous analysis of multi-component isotropic spectra. Formation constants and coordination modes",
abstract = "The formation constants and the isotropic ESR parameters (g-factors, 63Cu, 65Cu, 14N hyperfine coupling constants and relaxation parameters) of the various species were determined by the simultaneous analysis of a series of spectra, taken in a circulating system at various pH and ligand-to-metal concentration ratio. For both systems the new [CuLH]2+ complex was identified in acidic solutions. With the glycyl-L-serine ligand below pH 11.5 the same complexes and coordination modes are formed than with simple dipeptides. The side-chain donor group is bound only over pH 11.5 in the complex [CuLH-2(OH)]2-, where it is deprotonated and substitutes the carboxylate O in the third equatorial site. For the bis complex [CuLH-1(L)] - an isomeric equilibrium was shown, where the difference between the isomers was based on which of the donor atoms of the 'L' ligand, the peptide O or the amino N, occupies the fourth equatorial position, and which one is coordinated axially. The L-seryl-glycine ligand forms the same species as simple dipeptides and glycyl-L-serine up to pH 8. The only difference is that the axial binding of the alcoholic OH group fairly stabilizes the bidentate equatorial coordination of the 'L' ligand through the amino N and peptide O atoms in the [CuL]+ complex as well as in the major isomer of the [CuLH-1(L)]- complex. For this system we showed that (1) proton loss and the equatorial coordination of the alcoholic OH group occurs at relatively low pH (over pH 8-9), which results in the [CuL2H-2]2- complex with excess ligand, and also the newly identified species [Cu2L2H-4]2-: (2) this process is in competition with the proton loss of a coordinated water molecule. For both systems, the ESR-inactive species [Cu2L2H-3]- was also shown.",
keywords = "Coordination modes, Copper(II) complexes, ESR, Formation constants, Glycyl-L-serine, Isomerism, L-Seryl-glycine",
author = "T. Szab{\'o}-Pl{\'a}nka and Zsuzsanna {\'A}rkosi and A. Rockenbauer and L. Korecz",
year = "2001",
month = "4",
day = "30",
doi = "10.1016/S0277-5387(01)00758-6",
language = "English",
volume = "20",
pages = "995--1003",
journal = "Polyhedron",
issn = "0277-5387",
publisher = "Elsevier Limited",
number = "9-10",

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TY - JOUR

T1 - An ESR study of the copper(II)-glycyl-L-serine and copper(II)-L-seryl-glycine systems by the simultaneous analysis of multi-component isotropic spectra. Formation constants and coordination modes

AU - Szabó-Plánka, T.

AU - Árkosi, Zsuzsanna

AU - Rockenbauer, A.

AU - Korecz, L.

PY - 2001/4/30

Y1 - 2001/4/30

N2 - The formation constants and the isotropic ESR parameters (g-factors, 63Cu, 65Cu, 14N hyperfine coupling constants and relaxation parameters) of the various species were determined by the simultaneous analysis of a series of spectra, taken in a circulating system at various pH and ligand-to-metal concentration ratio. For both systems the new [CuLH]2+ complex was identified in acidic solutions. With the glycyl-L-serine ligand below pH 11.5 the same complexes and coordination modes are formed than with simple dipeptides. The side-chain donor group is bound only over pH 11.5 in the complex [CuLH-2(OH)]2-, where it is deprotonated and substitutes the carboxylate O in the third equatorial site. For the bis complex [CuLH-1(L)] - an isomeric equilibrium was shown, where the difference between the isomers was based on which of the donor atoms of the 'L' ligand, the peptide O or the amino N, occupies the fourth equatorial position, and which one is coordinated axially. The L-seryl-glycine ligand forms the same species as simple dipeptides and glycyl-L-serine up to pH 8. The only difference is that the axial binding of the alcoholic OH group fairly stabilizes the bidentate equatorial coordination of the 'L' ligand through the amino N and peptide O atoms in the [CuL]+ complex as well as in the major isomer of the [CuLH-1(L)]- complex. For this system we showed that (1) proton loss and the equatorial coordination of the alcoholic OH group occurs at relatively low pH (over pH 8-9), which results in the [CuL2H-2]2- complex with excess ligand, and also the newly identified species [Cu2L2H-4]2-: (2) this process is in competition with the proton loss of a coordinated water molecule. For both systems, the ESR-inactive species [Cu2L2H-3]- was also shown.

AB - The formation constants and the isotropic ESR parameters (g-factors, 63Cu, 65Cu, 14N hyperfine coupling constants and relaxation parameters) of the various species were determined by the simultaneous analysis of a series of spectra, taken in a circulating system at various pH and ligand-to-metal concentration ratio. For both systems the new [CuLH]2+ complex was identified in acidic solutions. With the glycyl-L-serine ligand below pH 11.5 the same complexes and coordination modes are formed than with simple dipeptides. The side-chain donor group is bound only over pH 11.5 in the complex [CuLH-2(OH)]2-, where it is deprotonated and substitutes the carboxylate O in the third equatorial site. For the bis complex [CuLH-1(L)] - an isomeric equilibrium was shown, where the difference between the isomers was based on which of the donor atoms of the 'L' ligand, the peptide O or the amino N, occupies the fourth equatorial position, and which one is coordinated axially. The L-seryl-glycine ligand forms the same species as simple dipeptides and glycyl-L-serine up to pH 8. The only difference is that the axial binding of the alcoholic OH group fairly stabilizes the bidentate equatorial coordination of the 'L' ligand through the amino N and peptide O atoms in the [CuL]+ complex as well as in the major isomer of the [CuLH-1(L)]- complex. For this system we showed that (1) proton loss and the equatorial coordination of the alcoholic OH group occurs at relatively low pH (over pH 8-9), which results in the [CuL2H-2]2- complex with excess ligand, and also the newly identified species [Cu2L2H-4]2-: (2) this process is in competition with the proton loss of a coordinated water molecule. For both systems, the ESR-inactive species [Cu2L2H-3]- was also shown.

KW - Coordination modes

KW - Copper(II) complexes

KW - ESR

KW - Formation constants

KW - Glycyl-L-serine

KW - Isomerism

KW - L-Seryl-glycine

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U2 - 10.1016/S0277-5387(01)00758-6

DO - 10.1016/S0277-5387(01)00758-6

M3 - Article

AN - SCOPUS:0035971323

VL - 20

SP - 995

EP - 1003

JO - Polyhedron

JF - Polyhedron

SN - 0277-5387

IS - 9-10

ER -