Electrochemical study of human foetal liver metallothionein: influence of the additions of cadmium and zinc

Dabrio, Marta; Rodríguez, A. R.

doi:10.1016/s0003-2670(99)00756-4

Cited by 12 publications

(10 citation statements)

References 29 publications

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“…In this figure all peaks which could be found in binary mixtures are presented. The polarographic peaks have been assigned in accordance with former studies on Cd, ZnMT [8][9][10][11][12][13][14][15][16] and on the cadmium and zinc complexed with FT using DPP [18,19,[21][22][23]. Peaks labelled β(Cd) and β(Zn) have been attributed to the oxidation of the mercury electrode in the presence of thiol groups complexed by cadmium and zinc, respectively.…”

Section: Resultssupporting

confidence: 80%

“…In this figure, the new peak labelled Cdβ' is shown and is attributed to the reduction of cadmium complexed by the β domain in a different complexation form to the Cdβ one. This new peak is labelled Cdβ' by analogy with peaks named CdT and CdT' in the study of MT [8][9][10][11][12][13][14][15][16] and CdFT and CdFT' obtained with the peptidic fragment FT in the presence of cadmium and/or zinc [17][18][19][20][21][22][23][24][25] in previous electrochemical works. Peaks have been resolved as mentioned and it is necessary to point out that, when Zn 2+ is in excess (Fig.…”

Section: Resultsmentioning

confidence: 89%

“…In previous DPP studies with MT [10,11,13,16] and with FT:Cd:Zn [19,20,25], the variation of pH has been seen to play an important role in the stability of one of the two cadmium complexes, CdT and CdT', and CdFT and CdFT'; in fact it is possible to provoke a change or to modify the proportion of both complexes by a mere change of the solution pH. When the pH is increased from 8 to 9.5 the transformation of CdT' peak, obtained in the presence of zinc, into the CdT peak occurs.…”

Section: Influence Of the Ph On The Complexation Forms Of Cadmiummentioning

confidence: 99%

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Complexing properties of the b metallothionein domain with cadmium and/or zinc, studied by differential pulse polarography

Dabrio¹,

Rodríguez²

2000

Analusis

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Mammalian metallothioneins (MT) containing 61 amino acids, of which 20 are cysteine have a structure comprising of two clusters. The α clusters correspond to the C terminal domain of residues 31-61 involving eleven cysteinic residues and the β cluster corresponds to the N-terminal domain of residues 1-30 with nine cysteine residues. All twenty cysteines participate in metal binding. While in the case of MT, their structure and characteristics have been studied using a great variety of analytical methods [1][2][3][4][5][6][7], relatively few studies have been performed with the α and β clusters separately probably due to the difficulties associated with their obtention. In fact these two domains are usually obtained by synthesis using either solid-phase and fragmentcondensation techniques or isolated by proteolysis of metallothioneins of different origin. Nevertheless the use of chemically synthesised and well-characterised separate α and β domains could be very interesting for the study of their metal binding properties and therefore contribute to the understanding of the behaviour of the entire MT.The aim of this research is the systematic study of the complexing properties of the β MT domain with cadmium and/or zinc using electroanalytical methods. These methods have been widely used by our team for the investigation of MT [8][9][10][11][12][13][14][15][16] and related molecules such as the peptidic fragment Lys-Cys-Thr-Cys-Ala (56-61) MT-1 (FT) alone and in the presence of cadmium and/or zinc [17][18][19][20][21][22][23][24][25]. In the case of MT and related molecules, the aminoacid chain is electroactive due to the presence of thiol groups. Moreover, the reduction of the cations, cadmium and zinc, is electrochemically reversible at the mercury electrode and, hence it is possible to obtain three different responses simultaneously for the sample under a given set of experimental conditions. In addition, the electrochemical response depends on the chemical form of the element and allows one to monitor the changes of the different species in solution as a function of different parameters.The β domain has been isolated using different methods [3,7] and its binding properties have been investigated using mainly spectroscopic methods [3,7,[26][27][28][29][30][31][32][33]. The synthesised peptide used in this work has been purchased from the Biochemistry Institute of Zurich University. The purity of this molecule was checked by both Dr. Klauser's team from Zurich University and our team using electrospray ionisation mass spectrometry (ESI-MS) [34,35].The binding properties have been studied, using differential pulse polarography, with different types of additions of metal ions to the apo-β domain and the inverted addition of the β MT domain to metal ions, the gradual addition of metal ions separately and the addition of both cations simultaneously.

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Section: Resultssupporting

confidence: 80%

Section: Resultsmentioning

confidence: 89%

Section: Influence Of the Ph On The Complexation Forms Of Cadmiummentioning

confidence: 99%

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Complexing properties of the b metallothionein domain with cadmium and/or zinc, studied by differential pulse polarography

Dabrio¹,

Rodríguez²

2000

Analusis

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“…The increase in heights of ZnT and ZnT signals have been shown during polarographic analysis of rabbit liver MT-2 [59], but the authors done their experiments directly in electrochemical cell, and then MT analysis could be influenced by metals contained in the supporting electrolyte. In spite of the differences between transfer technique and analysis in the cell, similar dependences of MT signals have been obtained [60,61]. The exact explanations about mechanisms influencing of MT are rather difficult.…”

Section: Influence Of a Supporting Electrolyte And Its Ph On Electrocmentioning

confidence: 57%

Determination of apo‐Metallothionein Using Adsorptive Transfer Stripping Technique in Connection with Differential Pulse Voltammetry

et al. 2007

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Links between metallothionein (MT), its structure and many biologically important pathways demonstrate the necessity of taking into account of studying the behavior of MT in different well defined mediums, which could help to model conditions in an organism easily. The main aim of this work was to prepare and determine apoMT by adsorptive transfer stripping technique (AdTS) in connection with differential pulse voltammetry (DPV). Particularly, we investigated the electrochemical behavior of MT measured on the surface of hanging mercury drop electrode in the presence of sodium chloride as supporting electrolyte using AdTS DPV with respect to study the effects of MT signals by different concentrations and pHs of the electrolyte. Then, we aimed at utilizing this technique to observe changes in MT which are dependent on using strong chelating compounds ethylendiamine-N, N, N', N'-tetraacetic acid (EDTA). Thanks to ability of EDTA to bind heavy metals from active center of enzymes and regulation proteins, we were able to prepare apoMT; that means, MT without any metal ion bound in its structure. Detection limit of apoMT at very short time of accumulation (t A ¼ 120 s) was 3 nM (20 ng/mL and/or 15 fmol in 5 mL drop; RSD ¼ 2 -5%) estimated by dilution of the analyzed solution until the signal disappeared. In addition, it was possible to decrease detection limit by extending of time of accumulation of apoMT on the surface of HMDE. We were able to detect 30 pM of apoMT (200 pg/mL and/or 150 amol in 5 mL drop) at t A ¼ 500 s.

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“…Different electrochemical techniques, under various experimental conditions, have been applied to the study of MTs [8±21]. Our team has been investigating, mainly using differential pulse polarography (DPP), a variety of MT samples from different origins, such as mammalian rabbit liver and horse kidney [9,10,12,13,19,20] and human fetal liver and adult kidney [17,18,21]. Cadmium and zinc contents are also seen to vary within these samples, containing a higher amount of Cd than Zn [9,10,12,13,18], almost only Cd [13,19] or almost only Zn [17, 19±21].…”

Section: Introductionmentioning

confidence: 99%

Study of Zinc Metallothionein from Rat Liver Using Electrochemical Techniques

Dabrio

Rodríguez

2000

Electroanalysis

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Studies of the electrochemical characterization for two isoforms of rat liver zinc metallothionein (MT) have been performed using differential pulse polarography (DPP) and square‐wave voltammetry (SWV). Three different responses due to the Zn(II) reduction have been distinguished, probably indicating different forms of complexation of zinc with the thionein. The influence of cadmium additions, as well as variation in the pH of the solution have been investigated. The additions of cadmium provoke alterations to the zinc complexes signals and the formation of cadmium complexes. However, depending on the initial concentration of zinc in the molecule, one of the two peaks of the Cd(II) reduction, attributed to two different forms of complexation of cadmium‐thionein, is prevalent. The stability of the MT in solution was checked as a function of time. All experiments were carried out in an inert atmosphere inside a glove box, to avoid oxidation of thiol groups of the MTs.

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Electrochemical study of human foetal liver metallothionein: influence of the additions of cadmium and zinc

Cited by 12 publications

References 29 publications

Complexing properties of the b metallothionein domain with cadmium and/or zinc, studied by differential pulse polarography

Complexing properties of the b metallothionein domain with cadmium and/or zinc, studied by differential pulse polarography

Determination of apo‐Metallothionein Using Adsorptive Transfer Stripping Technique in Connection with Differential Pulse Voltammetry

Study of Zinc Metallothionein from Rat Liver Using Electrochemical Techniques

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