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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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Voltametrie vysoce dispergovaných měděných prášků na rtuťových elektrodách
Heyrovský, Michael ; Korshunov, A. ; Bakardjieva, Snejana
Average size of majority of the tested powder particles was between 100 and 300 nm, which are kept in relatively stable dispersed form in electrolytic solutions by Brownian motion. Electrolytic activity of the particles was due to 10-30 nm thick surface layer of copper oxides, the outer side consisting of CuO, the inner side of Cu.sub.2./sub.O. The current due to electroreduction of surface copper oxides followed particulate mechanism: on fortuitous contact of particle with electrode surface an immediate transfer of a number of electrons takes place, determined by time of the contact and by several dynamic and steric factors. No diffusion flux of particles to electrode surface is established. The potential of particulate electroreduction is determined by electronic structure of the actual form of the solid state particle.
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Characteristics of solid amalgam electrodes different from HMDE
Josypčuk, Bohdan ; Navrátil, Tomáš
In the contribution are shown the results of experiments realized with solid amalgam electrodes containing, apart from mercury, also Ag, Cu, Ir, Au, Bi, or Cd. These results differ from those obtained with the hanging mercury drop electrode (HMDE). In some cases the solid amalgam electrodes enable the study of properties of compounds, which can not be observed on HMDE, usually due to the anodic dissolution of mercury. Anodic stripping voltammetry of Zn(II), Cd(II), Pb(II), Cu(II), and Fe(III), cathodic stripping voltammetry of adenine, guanine, phytochelatins, sulfides, and catalytic processes in presence of hydrogen peroxide, alcohols and Os-modified DNA, were studied with the working amalgam electrodes.
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The use of electrochemistry for the study of human metabolism of sulfur-containing compounds
Navrátil, Tomáš ; Petr, M. ; Šenholdová, Z. ; Přistoupilová, K. ; Přistoupil, T. I. ; Heyrovský, Michael ; Pelclová, D. ; Kohlíková, E.
The contribution deals with explanation of metabolism of supplemented creatine in human organism. This process differs from metabolism of natural endogenous creatine, which is excreted in form of creatinine. Exogenous creatine induces increase of peptide formation, of body mass, and of intracellular fluid; from 4 to 6 hours after creatine supplementation the level of thiodiglycolic acid and pH in urine rapidly increase, both of them then decrease rapidly to the original values.
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Multichannel device for electrochemical measurements
Navrátil, Tomáš ; Josypčuk, Bohdan
The article presents newly constructed 8-channel device, which enables sequential analysis realized on up to 8 different or equal sensors. The device is computer controlled, using PCI interface card. Special 8-chanel sensor, consisting of 8 various solid electrodes (e.g., 5 solid amalgam electrodes, and one electrode of each, glassy carbon, platinum, and gold) can be connected to this device.
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