Amine deprotonation in copper(III)-peptide complexes

Neubecker, Thomas A.; Kirksey, Sanford T.; Chellappa, K. L.; Margerum, Dale W.

doi:10.1021/ic50192a051

Cited by 42 publications

(34 citation statements)

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“…The autoxidation of Cu II G 4 and the decomposition of Cu III /G 4 /G 5 in the absence of sulfite were previously J. Braz. Chem.…”

Section: Introductionmentioning

confidence: 88%

“…1 Further studies 2 of the redox decomposition of Cu III G 4 at pH [6][7][8] 2-is the predominant species, showed that the initial products, are dehydropeptides which hydrolyze to form amides and corresponding carbonyl species. 4,5 Margerum et al 1,2,[4][5][6] studied the oxidation of Cu II G 4 complexes by oxygen in the presence and absence of sulfite, these data could not clearly explain the induction period and the autocatalytic behaviour. The present work brings more information about the reaction of Cu II G 4 with oxygen accelerated by sulfite.…”

Section: Introductionmentioning

confidence: 99%

“…4,5 Margerum et al 1,2,4-6 studied the oxidation of Cu II G 4 complexes by oxygen in the presence and absence of sulfite, these data could not clearly explain the induction period and the autocatalytic behaviour. The present work brings more information about the reaction of Cu II G 4 with oxygen accelerated by sulfite.…”

Section: Introductionmentioning

confidence: 99%

“…The symbols G n (G 4 , G 5 and G 6 ) are used here as general terms for tetraglycine, pentaglycine and hexaglycine respectively. (H -x G n ) -(x+1) refers to a peptide ligand with x deprotonated nitrogens coordinated to the copper ion.…”

Section: Introductionmentioning

confidence: 99%

“…Soc. studied by Margerum's research group. 1 (4) R is a reactive intermediate (either a carbon-centered free radical or a Cu(I) complex), RO 2 is either a peroxy radical or a copper(III) peroxide and G 4 DHP is a dehydropeptide which hydrolyzes to give glycylglycinamide and glyoxylglycine. 1 Further studies 2 of the redox decomposition of Cu III G 4 at pH [6][7][8] 2-is the predominant species, showed that the initial products, are dehydropeptides which hydrolyze to form amides and corresponding carbonyl species.…”

Section: Introductionmentioning

confidence: 99%

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Sulfite induced autoxidation of Cu(II)/tetra/ penta and hexaglycine complexes: spectrophotometric and rotating-ring-disk glassy carbon electrode studies and analytical potentialities

Alipázaga¹,

Bonifácio²,

Kosminsky³

et al. 2003

J. Braz. Chem. Soc.

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A oxidação de complexos de Cu(II) com tetra, penta e hexaglicina, em solução aquosa de tampão borato, pelo oxigênio dissolvido é fortemente acelerada por sulfito. A formação de complexos de Cu(III) com máximos de absorbância em 250 nm (ε = 9000 mol -1 L cm -1 ) e 365 nm (ε = 7120 mol -1 L cm -1 ) foi também caracterizada usando-se voltametria com eletrodo rotativo disco-anel, na qual componentes anódicos e catódicos foram observados em voltamogramas registrados em solução contendo Cu(II). Voltamogramas, obtidos com várias velocidades de rotação, mostraram que a espécie de Cu(III) gerada eletroquimicamente não é estável em toda a janela de tempo do experimento, e em solução contendo tetraglicina a corrente limite é controlada pela cinética de um equilíbrio envolvendo espécies de Cu(II). O valor calculado da constante de decomposição de primeira ordem foi 4,37x10 -3 s -1 . Experimentos eletroquímicos realizados em solução de Cu(II) após a adição de quantidades relativamente pequenas de sulfito demonstraram que a espécie de Cu(III), formada na reação química, é a mesma que foi coletada no eletrodo anel quando Cu(II) é oxidado no eletrodo disco. A concentração dos complexos de Cu(III) é proporcional à quantidade de sulfito adicionada e os resultados indicaram a possibilidade de desenvolvimento de um método analítico indireto para sulfito, com detecção espectrofotométrica ou amperométrica do produto quimicamente gerado.The oxidation of Cu(II) complexes with tetra, penta and hexaglycine in borate buffer aqueous solution, by dissolved oxygen is strongly accelerated by sulfite. The formation of Cu(III) complexes with maximum absorbances at 250 nm (ε = 9000 mol -1 L cm -1 ) and 365 nm (ε = 7120 mol -1 L cm -1 ) was also characterized by using rotating ring-disk voltammetry, whose anodic and cathodic components were observed in voltammograms recorded in solutions containing Cu(II). Voltammograms, obtained at various rotation speeds, showed that the Cu(III) species electrochemically generated is not stable over the entire time window of the experiment and in solutions containing tetraglycine the overall limiting current is controlled by the kinetics of an equilibrium involving Cu(II) species.The calculated first order rate constant of the decomposition was 4.37x10 -3 s -1 . Electrochemical experiments carried out in Cu(II) solutions after the addition of relatively small amounts of sulfite demonstrated that the Cu(III) species formed in the chemical reaction is the same as the one collected at the ring electrode when Cu(II) is oxidized at the disk electrode in ring-disk voltammetry. The concentration of Cu(III) complexes is proportional to the amount of added sulfite and the results indicated that indirect analytical methods for sulfite may be developed by means of spectrophotometric or amperometric detection of the chemically generated product.Keywords: copper (III), glycines, sulfite, catalysis, autoxidation, rotating ring disc electrode IntroductionThe present article is a comparative study of the sulfite induced oxidat...

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“…The autoxidation of Cu II G 4 and the decomposition of Cu III /G 4 /G 5 in the absence of sulfite were previously J. Braz. Chem.…”

Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Sulfite induced autoxidation of Cu(II)/tetra/ penta and hexaglycine complexes: spectrophotometric and rotating-ring-disk glassy carbon electrode studies and analytical potentialities

Alipázaga¹,

Bonifácio²,

Kosminsky³

et al. 2003

J. Braz. Chem. Soc.

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Metallo‐Drugs and Their Action

Dabrowiak

2009

Metals in Medicine

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Introduction of metallo-drugs into the body exposes them to reaction with many substances in the biological system. While the main targets for these agents are proteins and DNA, passage through the blood and eventually into the cell allows the metal complex to come in contact which substances that can modify its composition. The main focus of this chapter is on giving a brief overview of the structures of proteins and DNA and summarizing the ways in which these important biomolecules react with metal ions. Since many metalcontaining agents used in medicine have easily-displaced ligands, the manner in which complexes react with simple ions found in the blood and cells will also be presented and discussed. In addition to highlighting the biological chemistry of metallo-drugs, it is also important to outline how their pharmacological effects are measured and, since there is increasing demand for more effective agents, how a discovery made in the laboratory makes its way through the approval process to become a drug. Proteins as targets for metallo-drugsThe human body has tens of thousands of different proteins, involved in a variety of different catalytic, transport and structural roles. If a metal ion introduced into the body in the form of a metallo-drug attaches itself to a part of the protein that is critical for function, the ability of the protein to perform its biological task could be impaired, which could be enough to kill the cell. For example, many catalytically-active proteins called metallo-enzymes have naturally-occurring metal ions such as Zn þ2 or Cu þ1/þ2 in their active sites. Since the same ligands on the protein that bind to the naturally-occurring metal ion could also serve as donor atoms to the metal ion in a metallo-drug, addition of the drug to the protein could result in displacement of the natural metal ion, causing the enzyme to be catalytically inactive. Many proteins in the body use metal ions as a means of organizing their structure. Since some of these metallo-proteins are involved in gene expression and interact directly with DNA, disruption of their structure by substituting the natural metal ion with one supplied by a metallo-drug could affect the specificity and affinity of the interaction, thus influencing the ability of the cell to make the proper proteins for survival. Metals in MedicineJames C. DabrowiakStructurally, proteins are long polyamide polymers that are made up of monomer units called amino acids, the structures of which, along with their three-and one-letter amino acid codes, are shown in Figure 2.1. As is evident in the figure, all of the amino acids have an amino, a carboxylic acid and a hydrogen atom attached to the a-carbon atom of the compound, but the forth group on the a-carbon, called the side chain, characterizes each amino acid. Except for glycine, all of the common amino acids have four different groups attached to the a-carbon atom, which makes the atom, and thus the amino acid, chiral. With the exception of cysteine, which has the R absolute configuration...

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Metallo‐Drugs and Their Action

2017

Metals in Medicine

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Amine deprotonation in copper(III)-peptide complexes

Cited by 42 publications

References 12 publications

Sulfite induced autoxidation of Cu(II)/tetra/ penta and hexaglycine complexes: spectrophotometric and rotating-ring-disk glassy carbon electrode studies and analytical potentialities

Sulfite induced autoxidation of Cu(II)/tetra/ penta and hexaglycine complexes: spectrophotometric and rotating-ring-disk glassy carbon electrode studies and analytical potentialities

Metallo‐Drugs and Their Action

Metallo‐Drugs and Their Action

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