Spectrophotometric Determination of Copper in Lead, Tin, Aluminum, Zinc, and Their Alloys with Biscyclohexanone Oxalyldihydrazone.

Rohde, R. K.

doi:10.1021/ac60239a029

Cited by 19 publications

(7 citation statements)

References 6 publications

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“…PrP might also act as a sink for free copper to minimize the generation of oxygen radicals catalyzed by copper ions (Fenton reaction). Additional evidence for an involvement of copper in the pathogenesis of prion diseases comes from studies where cuprizone, a Cu 2+ chelating reagent (50), was administered to mice. Cuprizone induced pathological changes in the brains of mice comparable to those found in scrapie-infected mice (29,30).…”

Section: Discussionmentioning

confidence: 99%

Prion Protein Selectively Binds Copper(II) Ions

et al. 1998

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The infectious isoform of the prion protein (PrPSc) is derived from cellular PrP (PrPC) in a conversion reaction involving a dramatic reorganization of secondary and tertiary structure. While our understanding of the pathogenic role of PrPSc has grown, the normal physiologic function of PrPC still remains unclear. Using recombinant Syrian hamster prion protein [SHaPrP(29-231)], we investigated metal ions as possible ligands of PrP. Near-UV circular dichroism spectroscopy (CD) indicates that the conformation of SHaPrP(29-231) resembles PrPC purified from hamster brain. Here we demonstrate by CD and tryptophan (Trp) fluorescence spectroscopy that copper induces changes to the tertiary structure of SHaPrP(29-231). Binding of copper quenches the Trp fluorescence emission significantly, shifts the emission spectrum to shorter wavelengths, and also induces changes in the near-UV CD spectrum of SHaPrP(29-231). The binding sites are highly specific for Cu2+, as indicated by the lack of a change in Trp fluorescence emission with Ca2+, Co2+, Mg2+, Mn2+, Ni2+, and Zn2+. Binding of Cu2+ also promotes the conformational shift from a predominantly alpha-helical to a beta-sheet structure. Equilibrium dialysis experiments indicate a binding stoichiometry of approximately 2 copper molecules per PrP molecule at physiologically relevant concentrations, and pH titration of Cu2+ binding suggests a role for histidine as a chelating ligand. NMR spectroscopy has recently demonstrated that the octarepeats (PHGGGWGQ) in SHaPrP(29-231) lack secondary or tertiary structure in the absence of Cu2+. Our results suggest that each Cu2+ binds to a structure defined by two octarepeats (PHGGGWGQ) with one histidine and perhaps one glycine carbonyl chelating the ion. We propose that the binding of two copper ions to four octarepeats induces a more defined structure to this region.

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Section: Discussionmentioning

confidence: 99%

Prion Protein Selectively Binds Copper(II) Ions

et al. 1998

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“…ECS or CCS (about 0.2 g) was added to 100 mg/L of Cu (II) copper sulfate solution (200 ml, pH 5), and the mixture was shaken on a rotating shaker for 72 h at 150 rpm at 30ºC. The concentration of Cu (II) remaining in the supernatant was determined by means of spectrophotometry using the Cu (II) dicyclohexanoneoxaly dihydrazone colour system (Shimadzu UV-3100 spectrophotometer with 600 nm) [18]. The amount of Cu (II) adsorbed on ECS or CCS, Qe (mg/g dry weight), was calculated from the mass balance equation:…”

Section: Adsorption Experiments Of Ecs and Ccsmentioning

confidence: 99%

Preparation and Cu (II) Adsorption Characteristics of Carboxymethyl Cross-Linked Sewage Sludge

Wang

Zhang

2016

Pol. J. Environ. Stud.

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Sewage sludge was cross-linked with epichlorohydrin to increase its mechanical strength and applicability as an absorbent material. We investigated the effect of the conditions of the cross-linking reaction on the mechanical strength and Cu (II) adsorption capacity of epichlorohydrin cross-linking sewage sludge (ECS). Experimental results showed that cross-linking can raise signifi cantly the mechanical strength of sewage sludge. To improve the adsorption capacity of ECS, carboxymethyl cross-linked sewage sludge (CCS) with maximal adsorption capacity (65mg/g) for Cu (II) was synthesized from ECS by using chloroacetic acid as the etherifi cation agent. The experimental results showed that the adsorption properties of CCS for Cu (II) could best be described by the pseudo-second order model and Langmuir model, and the adsorption mechanism was ion exchange. Our data suggest that CCS is a promising absorbent for removal of heavy metals from wastewater.

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“…The suspension was shaken for another 2 h. After standing overnight, the solution was separated from the solid phase by centrifugation at 3000 rpm (3380g) for 10 min. The copper and Cr(VI) in solution were determined with a spectrophotometric method [23] and the diphenylcarbazide method [24], respectively. Finally, the pH values of the equilibrium solutions after adsorption were determined.…”

Section: Adsorption/desorption Experimentsmentioning

confidence: 99%