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Transport of divalent cations across the gel supported phospholipid membranes
Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír
This contribution deals with elucidation of principles of transporting processes of heavy metals (mainly lead, cadmium) across the biological membranes. The real membranes were for purposes of described experiments, replaced by model membranes, which were composed of phospholipid bilayers. Two different phorpholipids (1,2-dipalmitoyl-sn-glycero-3-phosphocholine and the mixture of phospholipids obtained from soybeans (under commercial name Asolectin)) were used as the building elements for the formation of these membranes on the surface of the constructed gel electrode. The registered transporting processes have been characterized using voltammetry, and electrochemical impendance spectrometry (EIS). The impact of some parameters on these systems and processes was investigated.
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Electrochemical behaviour of metallothioneins on silver amalgam electrodes
Šestáková, Ivana ; Josypčuk, Bohdan
Three different types of silver amalgam electrodes (p-AgSAE - polished silver solid amalgam electrode, m-AgSAE - mercury meniscus modified silver solid amalgam electrode and AgA-PE - silver amalgam paste electrode) were applied for voltammetric detection of metals bound in metallothionein (MT) molecule and for Brdička reaction with Co(III). The signals obtained with m-AgSAE and silver amalgam paste electrode correspond to signals observed on hanging mercury drop electrode (HMDE). Only p-AgSAE exhibits different behavior which is explained by the formation of AgMT. Formation of AgMT was demonstrated by dissapearance of Cd-Zn-MT peaks and by the increase of new peaks at -573 and -1050 mV, observed by differential pulse voltammetry on HMDE, when silver ions in excess were added to the Cd-Zn-MT solution.
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Transport of cadmium ions across model supported phospholipid membranes
Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír ; Štulík, Karel
These results report on experiments focussed on the formation of supported model phospholipid membranes, formed from phosphatidyl choline in the micrometric pores of hydrophilic polycarbonate supports, their chatacterization using voltammetry and electrochemical impendance spectrometry (EIS). Attention was paid transport of heavy metal ions (ions of cadmium, etc.) across these membranes in the presence or absence of ionophores (valinomysing and calciomycin) or in the presence of oxalic acid. The impact of some parameters on these systems and processes was investigated.
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Studium transportu iontů přes modelové fosfolipidové membrány
Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír
Synthetically prepared model phospholipid bilayers (PLBs) in the form of black membranes, vesicles or supported membranes, with incorporated ionophores or real ion channels (i.e., artificially synthesized or gained from real living cells, e.g. protoplasts) are promising for study and simulations of transporting processes across the real cell membranes and the membranes surrounding sub-cellular structures. The electrochemical methods were found to be very suitable and sensitive enough for characterization of such processes.
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Přenos kadmia přes biologické membrány
Šestáková, Ivana ; Navrátil, Tomáš
From complexing ligands, low molecular weight organic acids are important as plant exudates in soil solution, whereas sulfur containing - ligands phytochelatins - sequester Cd2+ inside the cell vacuole. Voltammetrically determined fytochelatins concentration could be correlated with total Cd concentration found in different parts of plant.
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Cd and Pb Speciation in Thlaspi caerulescens Presl Rhizosphere
Jakl, M. ; Jaklová Dytrtová, J. ; Šestáková, Ivana ; Tlustoš, P.
In this study the influence of Thlaspi caerulescens Presl rhizosphere on Cd and Pb complex formation and their total amount in soil solution of contaminated fluvisol from Litavka river alluvium was investigated. The soil solution was sampled from roots surrounding and from bulk behind rhizobag. The content of free Cd and Pb ions was measured by the differential pulse anodic stripping voltammetry in unchanged pH and in pH 2 in rhizosphere and bulk soil. The bimetallic Cd-Pb-oxalic acid complexes were detected in unchanged pH only.
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Patch Clamp Technique – The Tool for Ions Transport across Model and Real Biological Membranes
Navrátil, Tomáš ; Jaklová Dytrtová, J. ; Jakl, M. ; Šestáková, Ivana ; Mareček, Vladimír ; Krůšek, Jan
The project is aimed at the preparation and characterization of model and/or real phospholipid bilayers at stabilized phase boundaries enabling studies of transfer of charged and uncharged species between the two phases. The best way for investigation of inorganic ion transfer is provided by using mercury as one of the phases, in view of the large amount of the relevant electrochemical data available, whereas the transfer of more complex species is better studied in the system of an organic and an aqueous phase stabilized by (agar) gel. The results contribute to the understanding of ion transport across real membranes. Polypeptides and peptides capable forming ionic channels and enabling transport of various ions and molecules across the membranes, will be incorporated into the model membranes. The possibilities of transport of selected compounds across the model membrane will be investigated using cell permeable peptides as well.
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