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

Abstract

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.

Chemical Speciation of Copper in a Salt Marsh Estuary and Bioavailability to Thaumarchaeota

“…Previous measurements suggest that thiols bind copper as a Cu(I) species (Leal and van den Berg, 1998;Konigsberger et al, 2015;Barman et al, 2016). From our assumption based on the correlation between thiourea-type thiols and L 1 , an important deduction from this work is that most of the copper in these coastal waters would appear to occur in the reduced form of Cu(I).…”

“…As well as cell exudates, sources of thiols include pore waters (Zhang et al, 2004) and sewage effluents (Dryden et al, 2007). RSS typically form Cu(I) complexes (Leal and van den Berg, 1998;Konigsberger et al, 2015) although Cu(II)-thiolates have been generated artificially (Kitajima et al, 1990). Different thiols bind copper with a range of log K ′ CuL values, typically log K ′ CuL = 12-14 (Laglera and van den Berg, 2003) in salinities from estuarine to seawater.…”

Kayser-Fleischer-Ring – kann eine frühe Diagnosestellung den Krankheitsverlauf von Morbus Wilson verbessern?

“…Man geht davon aus, dass dies im Zusammenhang mit dem Fluss des Kammerwassers zusammenhängt [2]. Der Beginn zeigt sich i. d. R. von 10 bis 2 Uhr, breitet sich dann inferior und anschließend zirkulär aus [3]. Die Kupferpartikel infiltrieren wahrscheinlich die Descemet über das Kammerwasser durch das Endothel hindurch.…”

Translation of a chemical reaction to electrical signal generation: an organic–inorganic complexation strategy

“…The formation of Cu(I) complexes with cysteine was well-documented in literature. 16,17,24 In the case of D (Ia), the I-V characteristic exhibited a deviation from D (I) but without a proper resistive switching, while the devices D (Ib) and D (Ic) exhibited a resistive switching with an ON-to-OFF ratio of 5 Â 10 À2 and B10 1 , respectively. In the case of devices D (Ia) and D (Ic), the conductivity values were close to the devices made with CuP, D (I), and cysteine, D (II), respectively, due to the incorporation of low and high concentrations of cysteine into the device D (I).…”

“…16 The formation constants of Cu-complexes with cysteine based on the thermodynamic model confirmed that a univalent copperion is predominant in blood plasma, aqueous humour and cornea of the human eye. 17 The Cu(I)-cysteine complex also acts as a hole scavenging co-catalyst that influences the activity of CdSe for hydrogen production in the presence of visible light and also minimizes the electron-hole pair recombination due to photo-excitation. 18 The translation of a chemical reaction to electrical signal generation is a well-established method in electrochemical sensing applications.…”