Effects of Reduced Glutathione, Surface Active Agents, and Ionic Strength on the Detection of Metallothioneins by Using of Brdicka Reaction

Abstract

We investigated the effects of two surface active agents (sodium dodecyl sulfate, SDS, and polyoxyethylene sorbitol, , ionic strength and reduced glutathione (GSH) on MT signals measured by adsorptive transfer stripping differential pulse voltammetry Brdicka reaction. If we compared the GSH and MT signals at the accumulation time of 120 s, the MT signal was more than two hundred times higher than the GSH one. The influence of Tween-20 was investigated in a broad concentration range (from 10 À8 to 10 À11 %, v/v). We found that the catalytic Cat2 signal decreased for more than 60% with increasing Tween-20 content. In the case of using SDS (10 À3 -10 À6 M), the increase of Cat2 peak in the presence of the highest SDS concentration was determined. The height of Cat2 peak enhanced with increasing ionic strength mimicking by NaCl concentration. Based on the enhancement of the Cat2 peak we determined the ionic strength of fibroblasts sample and recalculated the concentration of MT determined there. Methods for determination of MT in clinical samples are often based on relatively time-consuming and not enough sensitive immunohistochemistry [8]. Thus proposing new methods and procedures for routine and sensitive detection of MT is needed. More than 70 years ago Brdicka discovered the catalytic evolution of hydrogen in the presence of cobalt(III) solution and proteins [9]. Brdicka used the catalytic signals to determine the changes of the proteins concentration in a blood serum of patients with cancer [10]. Unfortunately, the electrochemical techniques have been replaced by electromigration methods and other robust analytical techniques in the following decades. Ten years ago the catalytic signals were investigated again by means of the new electrochemical instruments and methods to treat the data obtained [11 -19]. Recently we have studied the electrochemical behavior of metallothionein at the surface of mercury electrode by chronopotentiometric stripping voltammetry and by differential pulse voltammetry both coupled with adsorptive stripping transfer technique [12, 20 -24].In spite of the fact that electrochemical techniques have been utilizing for determination of MT in many types of real samples, the effects of fundamental physicochemical properties of samples such as ionic strength, content of active surface agents as well as content of low molecular mass thiols are not clear. Thus we investigated the effects of two surface active agents, ionic strength and reduced glutathione as the most abundant low molecular mass thiol on MT signals measured by adsorptive transfer stripping differential pulse voltammetry Brdicka reaction.Many scientists have been paying attention to electrochemical determination of metallothionein as stress marker in environmental research. However it seems that these proteins can play somewhat key role in the processes of tumor development and this role remains still unclear. Therefore, the increased interest in metallothionein deter-640

Study of Interactions between Metallothionein and Cisplatin by using Differential Pulse Voltammetry Brdicka´s reaction and Quartz Crystal Microbalance

“…The concentration of MT and cisplatin used in this study was similar to those found in the body, where the concentrations of these compounds ranges from sub-units to units μM [11,21,64,65]. Concerning our findings, we have discovered that a new signal appeared after MT-cisplatin interaction, which correlated well both with time of interaction and concentration of the drug.…”

Comparison of Metallothionein Detection by Using Brdicka Reaction and Enzyme‐Linked Immunosorbent Assay Employing Chicken Yolk Antibodies

“…Moreover, low-molecular mass thiols (cysteine, glutathione and SH-rich peptides), which can be hardly denatured by heat treatment, can interfere with electrochemical MT determination too [92]. Nevertheless, we proved that both low molecular thiols and non-heateddegradable proteins did not interfere the Brdickas measurements [24]. Surface active compounds present in biological samples can influence the adsorption of the analytes onto the electrode surface, however it was shown that the influence is minimal in this type of a solution [24].…”

“…Nevertheless, we proved that both low molecular thiols and non-heateddegradable proteins did not interfere the Brdickas measurements [24]. Surface active compounds present in biological samples can influence the adsorption of the analytes onto the electrode surface, however it was shown that the influence is minimal in this type of a solution [24].…”

Complexes of glutathione with heavy metal ions as a new biochemical marker of aquatic environment pollution

“…For more details on adsorption of thiols on the surface of mercury electrodes, see previous studies [17,21,22]. Thanks to the free ÀSH moiety, GSH is a highly electroactive molecule, but its low molecular mass negatively influences adsorption on a working electrode surface [23]. In spite of this drawback, it is possible to study even such a small molecule by this method (Fig.…”