Untitled

Bagiyan, G. A.; Koroleva, I. K.; Soroka, N. V.; Ufimtsev, A. V.

doi:10.1023/a:1024761324710

Cited by 158 publications

(100 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…28 Consistent with the present findings, Harman and Sóvágó 49 have pointed out that the degree of formation and stoichiometry of M n+ PSH polynuclear complexes should be markedly different from those for M n+ CSH due to steric inhibition by the -methyl substituents in the former. This insight contrasts markedly with earlier investigations 25,45,46 that assumed the same model for Cu(I)CSH and Cu(I)PSH.…”

Section: Also Included Incontrasting

confidence: 99%

“…Table 4 are literature values of the formation constants for the Cu(I)PSH system obtained under conditions broadly similar to the present work. The presence of Cu(PS)  has been claimed in several studies 45,46 but there are large differences in the reported formation constants. The present result (lg 110 = 12.42) is about the average of the earlier values, although it should be noted that the work of Vortisch et al 45 is not strictly comparable with the present study as their measurements were made in aqueous acetonitrile solutions.…”

Section: Glutathionementioning

confidence: 96%

“…36,37,47 Regardless, a value of  110 is required to achieve convergence and to fix the numerical values of the other formation constants, even though the value chosen has little effect on the stepwise formation constants of subsequent species. The value selected, lg 110 = 13.13, was determined polarographically at the same ionic strength and temperature in this laboratory 48 and is the approximate average of the lg 110 values reported by Vortisch et al 45 and Bagiyan et al 46 .…”

Section: Also Included Inmentioning

confidence: 98%

“…The tendency of CSH to form protonated and polynuclear complexes with a variety of metal ions is well known. 23 Interestingly, Bagiyan et al 46 indicated that protonated complexes of Cu(CS)  formed readily during their pH-metric titrations but only reported a value for  110 (Table 5). 28 Consistent with the present findings, Harman and Sóvágó 49 have pointed out that the degree of formation and stoichiometry of M n+ PSH polynuclear complexes should be markedly different from those for M n+ CSH due to steric inhibition by the -methyl substituents in the former.…”

Section: Also Included Inmentioning

confidence: 99%

See 3 more Smart Citations

Formation constants of copper(i) complexes with cysteine, penicillamine and glutathione: implications for copper speciation in the human eye

Königsberger

Hefter

et al. 2015

Dalton Trans.

View full text Add to dashboard Cite

Protonation constants for the biologically-important thioamino acids cysteine (CSH), penicillamine (PSH) and glutathione (GSH), and the formation constants of their complexes with Cu(I), have been measured at 25 C and an ionic strength of 1.00 mol dm 3 (Na)Cl using glass electrode potentiometry. The first successful characterisation of binary Cu(I)CSH and Cu(I)GSH species over the whole pH range was achieved in this study by the addition of a second thioamino acid, which prevented the precipitation that normally occurs. Appropriate combinations of binary and ternary (mixed ligand) titration data were used to optimise the speciation models and formation constants for the binary species. The results obtained differ significantly from literature data with respect to the detection and quantification of protonated and polynuclear complexes. The present results are thought to be more reliable because of the exceptionally wide pH and concentration ranges employed, the excellent reproducibility of the data, the close agreement between the calculated and observed formation functions, and the low standard deviations and absence of numerical correlation in the constants. The present formation constants were incorporated into a large Cu speciation model which was used to predict, for the first time, metal-ligand equilibria in the biofluids of the human eye. This simulation provided an explanation for the precipitation of metallic copper in lens and cornea, which is known to occur as a consequence of Wilson's disease.

show abstract

Section: Also Included Incontrasting

confidence: 99%

Section: Glutathionementioning

confidence: 96%

Section: Also Included Inmentioning

confidence: 98%

Section: Also Included Inmentioning

confidence: 99%

See 2 more Smart Citations

Formation constants of copper(i) complexes with cysteine, penicillamine and glutathione: implications for copper speciation in the human eye

Königsberger

Hefter

et al. 2015

Dalton Trans.

View full text Add to dashboard Cite

show abstract

“…The addition of 2 mM EDTA to the buffer was essential to avoid thiol oxidation 7 and superior to any attempts using a protective argon atmosphere. To determine the second-order rate constants (k 2 ), pseudo-first-order kinetic conditions were used to measure the exponential decay of chalcones when a thiol is added.…”

Section: Communication Organic and Biomolecular Chemistrymentioning

confidence: 99%

Reactivity assessment of chalcones by a kinetic thiol assay

et al. 2013

View full text Add to dashboard Cite

The electrophilic nature of chalcones (1,3-diphenylprop-2-en-1-ones) and many other α,β-unsaturated carbonyl compounds is crucial for their biological activity, which is often based on thiolmediated regulation processes. To better predict their biological activity a simple screening assay for the assessment of the secondorder rate constants (k 2 ) in thia-Michael additions was developed.Hence, a clear structure-activity relationship of 16 differentially decorated hydroxy-alkoxychalcones upon addition of cysteamine could be established. Moreover, amongst other naturally occurring α,β-unsaturated carbonyl compounds k 2 values for curcumin and cinnamaldehyde were gained while cinnamic acids or esters gave no or very slow reactions.Chalcones (1,3-diphenylprop-2-en-1-ones) are natural products from the class of plant polyphenols and the biochemical precursors of cyclic flavonoids. They display anti-inflammatory, antioxidative, anti-mitotic, bactericidal, antifungal, antimalarial, antileishmanial to chemoprotective and chemopreventive activity, but also cytotoxic and antiviral properties were found. 1 Their activity is mostly based either on the Michael acceptor activity of the α,β-unsaturated carbonyl system, or their radical scavenging or reductive potential which are often referred to as antioxidative behaviour.2 The Michael acceptor activity is affected both by the decoration of the aromatic rings, and also, even more effectively, by an α-X-substitution of the double bond of the enone system. 3 Despite the fact that Michael acceptors are a neglected class of compounds in drug development their unique capability to address certain cysteine residues qualifies them as valuable tools to modulate biological activity. 1d Nevertheless, there is no simple, efficient quantitative method to assess and compare the reactivity of different chalcones and other α,β-unsaturated carbonyl compounds to be able to identify suitable electrophiles. Therefore, we developed a facile screening assay to determine the second-order rate constants (k 2 ) of chalcones in thia-Michael additions. As a starting point, the reactivity of the α-H-chalcones was assessed since this is the pattern found in almost all natural products of this class -the only exception being the α-hydroxychalcones.

show abstract

3‐Mercaptopropionate Dioxygenase (MDO)

Schmittou

Solano

Kiser

et al. 2023

Encyclopedia of Inorganic and Bioinorganic Chemistry

View full text Add to dashboard Cite

Bacterial 3‐mercaptopropionate dioxygenase (MDO) is a mononuclear nonheme iron dioxygenase that catalyzes the O 2 ‐dependent oxidation of 3‐mercaptopropioniate (3MPA) to produce 3‐sulfinopropionate (3SPA). MDO is a member of the cupin superfamily of proteins and therefore shares a similar active site architecture as mammalian and bacterial cysteine dioxygenases (CDOs). However, unlike CDOs, which exhibit near exclusive specificity for l ‐cysteine (CYS), MDOs are more flexible with respect to accommodating other thiol‐bearing substrates of comparable size to 3MPA. The active site of MDO and CDO share two major structural features. First, they both contain a mononuclear nonheme iron site coordinated by three histidine residues. Since all protein‐derived ligands occupy one face of an octahedron, binding of dioxygen and organic substrate occurs at the opposite face of the 3‐His facial triad. Second, both enzymes share a conserved sequence of outer Fe‐coordination sphere amino acids (Ser, His, and Tyr) positioned adjacent to the iron site (∼ 4 Å). These residues participate in an extended proton relay network which ultimately donates an H‐bond to the enzymatic Fe‐site. To date, MDOs have only been identified among Gram‐negative soil proteobacteria. It is believed that the high concentration of 3MPA present in coastal sediments can be attributed to bacterial catabolism of organosulfur compounds present in saline environments. Indirect evidence also suggests that 3MPA may play a more central role in bacterial sulfur metabolism than currently understood.

show abstract

Untitled

Cited by 158 publications

References 14 publications

Formation constants of copper(i) complexes with cysteine, penicillamine and glutathione: implications for copper speciation in the human eye

Formation constants of copper(i) complexes with cysteine, penicillamine and glutathione: implications for copper speciation in the human eye

Reactivity assessment of chalcones by a kinetic thiol assay

3‐Mercaptopropionate Dioxygenase (MDO)

Contact Info

Product

Resources

About