Katarzyna Kurzątkowska

Native and denatured forms of proteins can be discriminated at edge plane carbon electrodes.

In an attempt to develop a label-free electrochemical method for detection of changes in protein structures based on oxidizability of tyrosine and tryptophan residues we tested different types of carbon electrodes. We found that using edge plane pyrolytic graphite electrode (EPGE) we can discriminate between native and denatured forms of human serum albumin (HSA) and of other proteins, such as bovine and chicken serum albumin, aldolase and concanavalin. Treatment of natively unfolded α-synuclein with 8 M urea resulted only in a small change in the tyrosine oxidation peak, in a good agreement with absence of highly ordered structure in this protein. Using square wave voltammetry with EPGE we were able to follow the course of HSA denaturation at different urea concentrations. The electrochemical denaturation curve agreed reasonably well with that based on intrinsic fluorescence of tyrosine and tryptophan. It can be expected that the electrochemical method will be applicable to a large number of proteins and may become useful in biomedicine and proteomics.

Immobilization of His-tagged kinase JAK2 onto the surface of a plasmon resonance gold disc modified with different copper (II) complexes.

New surface plasmon resonance (SPR) sensing platforms which consists of copper (II) complexes of a pentetic acid thiol ligand (DPTA-Cu(II)) and of a thiol derivative of dipyrromethene (DPM-Cu(II) created on the surface of gold SPR disc were applied to oriented immobilization of His-tagged Janus kinase 2 (GST-His6-JAK2). This method is based on the covalent bond formation between histidine from a His-tag chain of a protein and Cu(II) centres from the complexes. The kinetic and thermodynamic parameters of the oriented immobilization of GST-His6-JAK2 protein to DPTA-Cu(II) and DPM-Cu(II) complexes attached to the Au surface of a SPR disc were discussed.

Systematic study of interaction of the neutral form of anilines with undecylcalix[4]resorcinarene derivatives by means of potentiometry

The elucidation of the mechanism of potentiometric signals generation by liquid membrane electrodes incorporating undecylcalix[4]resorcinarene derivatives upon stimulation by uncharged aniline derivatives is the main aim of the research presented. A series of molecules which play the role of host and guests in the molecular recognition process occurring at the aqueous–organic membrane interface were explored. It was proved that in the conditions where all aniline derivatives exist as uncharged molecules, cationic potentiometric signals were observed for all undecylcalix[4]resorcinarene liquid membrane electrodes. The main parameters crucial for this phenomenon are the acidity/basicity of the hosts as well as the guests. The lipophilicity of the guests plays a secondary role.

Gold Electrodes Modified with Calix[4]arene for Electrochemical Determination of Dopamine in the Presence of Selected Neurotransmitters

Here, we present an electrochemical sensor based on gold electrodes modified with calix[4]arene functionalized with carboxypiperidino groups at the upper rim. It has been demonstrated that these groups are involved in a complex formation with dopamine (DA) on the surface of gold electrodes. The supramolecular complex calix[4]arene–DA created on the gold electrode surface has been characterized electrochemically and the measuring conditions have been optimized. The presented sensor displayed a detection limit in the pM range. The DA determination was performed successfully in the presence of ascorbic acid, uric acid and selected neurotransmitters.