Complexation properties of the metallothionein fragment Lys-Cys-Thr-Cys-Cys-Ala [56-61] MT I with zinc using square wave voltammetry

Nieto, Óscar; Rodríguez, A. R.

doi:10.1016/0302-4598(96)01913-7

Cited by 33 publications

(21 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3A f), the peak potential does not coincide with the one of free Zn 2+ but shifts to more positive values than are attributed to Znβ'. This behaviour was already noticed during zinc and cadmium additions to MT or FT; nevertheless the peak labelled Zn is not clearly associated with Zn 2+ nor with a weak complex of zinc with the organic molecules [12,15,20,24].…”

Section: Resultsmentioning

confidence: 74%

“…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%

“…When the β domain is solely present in the supporting electrolyte, the peak named β is only observed in some cases using DPP; however if square wave voltammetry is used, this β peak is very well defined and detected at -709 mV (results not shown). This peak is attributed to the oxidation of the mercury electrode in the presence of free thiol groups and due to an adsorption process [14,[20][21][22][23][24].…”

Section: Resultsmentioning

confidence: 99%

“…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%

“…Experimental parameters used had been optimised in previous works [20]. In all cases, the drop size is the same and depends on the number of pulses (np = 5) and the pulse width (pw = 10 msec).…”

Section: Electrochemical Proceduresmentioning

confidence: 99%

See 4 more Smart Citations

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

Dabrio¹,

Rodríguez²

2000

Analusis

View full text Add to dashboard Cite

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.

show abstract

Section: Resultsmentioning

confidence: 74%

Section: Resultsmentioning

confidence: 89%

Section: Resultsmentioning

confidence: 99%

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

confidence: 99%

Section: Electrochemical Proceduresmentioning

confidence: 99%

See 3 more Smart Citations

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

Dabrio¹,

Rodríguez²

2000

Analusis

View full text Add to dashboard Cite

show abstract

Voltammetric Methods for Speciation of Plant Metallothioneins

1998

View full text Add to dashboard Cite

Cd, Cu and Zn complexes of two synthetically prepared peptides, (g-Glu-Cys) 2 -Gly and (g-Glu-Cys) 3 -Gly, were studied as models of plant metallothioneins by several voltammetric methods. Reduction peak of the complex in which the stechiometric ratio of molar concentrations of Cd(II) and peptide corresponds to coordination of one Cd(II) by four sulfur atoms (E p = ¹814 mV to ¹910 mV, DPV) is suitable for speciation. CSV after adsorption of Cu(I) complex on HMDE is also convenient, and two peaks (E p = ¹817 mV to ¹850 mV and E p = ¹940 mV to ¹953 mV) are attributed to plant MT with Cu(I). Cd and Cu complexes can be distinguished by different dependences for adsorptive accumulation of complexes on HMDE. In both cases the presence of zinc ions interferes with voltammetric speciation. Results of voltammetric studies were applied to the analysis of algal extracts, prepared from alga Chlorella, which was grown in cadmium enriched medium. Successful voltammetric identification of plant metallothionein in this type of material has been performed, in agreement with results from AAS and UV spectroscopy.

show abstract

Complexation Properties of the Metallothionein Fragment Lys-Cys-Thr-Cys-Cys-Ala [56-61] MT I with Zinc and Cadmium Using Square Wave Voltammetry

Nieto

Rodríguez²

1999

Electroanalysis

Self Cite

View full text Add to dashboard Cite

An electrochemical study using square wave voltammetry of the complexing properties of the peptide Lys-Cys-Thr-Cys-Cys-Ala [56±61] MT 1 (FT), a part of the metallothionein structure, with cadmium and zinc was performed. The applied technique allows one to obtain wellde®ned peaks corresponding to the free metal ions as well as providing evidence that different forms of coordination of Cd(II) and Zn(II) with the peptide exist. FT is capable of complexing Cd 2 and Zn 2 separately in a concentration equal to FT, obtaining complexes with a ratio of 1 : 1. However, the total metal ion concentration bound to the FT is higher when both cations are simultaneously present. The maximum total concentration that can be complexed with FT is a ratio of [Zn] : [Cd] : [FT] like 0.6 : 1.0 : 1.0 which leads to the ratio of Zn 4 Cd 7 S 21 , comparable to that of the metallothionein structure. The coordination of Cd(II) with FT not only depends on the Cd : FT ratio, but also on the proportion in which Zn(II) is added. However, the Zn(II) complexes are not affected by the presence of Cd-FT complexes in solution. The complexation equilibrium was investigated going from acid to basic solutions and viceversa. From the slopes of the variation E p f (pH), the number of thiol groups at which the cations are bound were evaluated. This study allows us to enable comparisons between the behavior of [Zn] : [Cd] : [FT] with that of Cd,Zn metallothioneins.

show abstract

Complexation properties of the metallothionein fragment Lys-Cys-Thr-Cys-Cys-Ala [56-61] MT I with zinc using square wave voltammetry

Cited by 33 publications

References 12 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

Voltammetric Methods for Speciation of Plant Metallothioneins

Complexation Properties of the Metallothionein Fragment Lys-Cys-Thr-Cys-Cys-Ala [56-61] MT I with Zinc and Cadmium Using Square Wave Voltammetry

Contact Info

Product

Resources

About