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Complexation of zinc ions by the phytochelatin PC2
Šestáková, Ivana ; Serrano, N. ; Diaz-Cruz, J. M. ; Arino, C.
Contrary to mammaliam metallothioneins, where Zn(II) is coordinated by four sulphur atoms, no structural studies are available for complexes of Zn- phytochelatins. Based on earlier experiences with electrochemical study of complexes of simplest phytochelatin-PC2- with cadmium ions, voltammetry and constant current chronopotentiometry on HMDE were used to study complexation of this phytochelatin with zinc ions. Overlapping of signals was overcome by the application of multivariate curve resolution method by alternating least squares. As result, structures with two or four sulphur atoms participating on Zn(II) complexation were suggested.
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Reproducibility of working electrodes in voltammetry
Josypčuk, Bohdan ; Heyrovský, Michael
In voltammetry the working electrode is the source of signal from which the due information is gained. A transition from the dropping mercury electrode to any kind of stationary electrode is inevitably accompanied by worsened reproducibility of measurements, the transition to the hanging mercury drop electrode is accompanied by a certain instrumental complication. When solving a concrete task, the precision of reproducibility of measurements often becomes the decisive factor for selecting a particular type of working electrode, or for taking voltammetry as the method of choice. This work is the beginning of a wider study which includes comparison of different working electrodes and finding of optimal conditions guaranteed reproducible measurements of various electrode processes (reduction, oxidation, accumulation, adsorption and catalysis).
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The application of Brdička reaction for determination of phytochelatins in real samples of barley and thermophilic cyanobacterium grown in the presence of cadmium ions
Čížková, Petra ; Fedjuk, K. ; Šestáková, Ivana
Heavy metals represent important group of environmental contaminants. Ions of heavy metals (Cd, Pd, Cu, Hg, Zn and Ni) are released into soil solutions as a consequence of soils acidification, among others. Their presence has imminent influence on physiological procedures in plants, which have developed different mechanisms of adaptation on such conditions. One of mechanisms for plants tolerance towards heavy metal ions is their inactivation by binding on polypeptides or small proteins with high cysteine content, named phytochelatins (PC) or metallothioneins. Their function has been studied in particular at man and animals.
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