Anodic stripping voltammetry in the complexation study of the peptide Lys-Cys-Thr-Cys-Cys-Ala (56-61)MT I and cadmium: application in determination of complexing capacity and stability constant

Erk, Marijana; Raspor, Biserka (2001) Anodic stripping voltammetry in the complexation study of the peptide Lys-Cys-Thr-Cys-Cys-Ala (56-61)MT I and cadmium: application in determination of complexing capacity and stability constant. Journal of Electroanalytical Chemistry, 502 (1-2). pp. 174-179. ISSN 0022-0728

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Abstract

A study of Cd complexation with the peptide Lys-Cys-Thr-Cys-Cys-Ala thionein fragment [56-61] MT I (FT) was performed in the differential pulse anodic stripping voltammetric (DPASV) mode. Amperometric titrations of FT with cadmium standard solution were performed in 0.59 mol dm^ -3 NaCl at pH 7.9, and at a constant temperature of 25.0 °C. The signal of FT without cadmium has the peak potential at Ep(FT) = -0.52 V (vs. an Ag/AgCl electrode). As the titration with CdCl_2 proceeds a signal related to CdFT complex appears at the potential Ep(CdFT) = -0.67 V. When the available complexing sites on FT are saturated the signal of Cd ionic appears. From the amperometric titration data the capacity of FT to complex Cd (C_L) and the apparent stability constant of the CdFT complex (K') using modified van den Berg-Ružić-Lee method were determined. Mean value of the stability constant corrected for the partition of the hydrated Cd^2+ ion within the ionic cadmium concentration is 5.3x10^10 dm^3 mol^-1. In addition the titration of the constant Cd^2+ concentration with FT was performed. Due to the excess of cadmium over the FT and vice versa the existence of the complexes of different stoichiometry are proposed causing the poorly resolved signal.

Item Type:	Article
Uncontrolled Keywords:	metallothionein fragment; cadmium; complexation; differential pulse anodic stripping voltammery
Subjects:	NATURAL SCIENCES > Chemistry NATURAL SCIENCES > Interdisciplinary Natural Sciences
Divisions:	Division for Marine and Enviromental Research
Depositing User:	Marijana Erk
Date Deposited:	10 Jul 2015 12:20
URI:	http://fulir.irb.hr/id/eprint/2067
DOI:	10.1016/S0022-0728(01)00356-4

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