Native and denatured forms of proteins can be discriminated at edge plane carbon electrodes
ABSTRACT 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.
- SourceAvailable from: Jan TkacChemical Reviews 03/2015; 115(5):2045–2108. DOI:10.1021/cr500279h · 45.66 Impact Factor
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ABSTRACT: Rituximab (RTX) is a human/murine chimeric monoclonal antibody (mAb) that specifically targets the transmembrane protein CD20 of B-cells. The oxidation mechanism of native and denatured RTX was investigated on glassy carbon electrode. The denaturing agent sodium dodecyl sulfate and the redutancts tris(2-carboxyethyl)phosphine and dithiothreitol were used. Significant differences were observed for native and denatured RTX oxidation due to morphological changes and unfolding of the RTX native structure. Native RTX presented only one oxidation peak of tyrosine and tryptophan residues, whereas in denatured RTX were detected three peaks corresponding to the oxidation of tyrosine, tryptophan and histidine residues.Electroanalysis 04/2013; 25(4):1029-1034. DOI:10.1002/elan.201200552 · 2.50 Impact Factor
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ABSTRACT: We introduce the concept of screen-printed back-to-back electroanalytical sensors where in this facile and generic approach, screen-printed electrodes are printed back-to-back with a common electrical connection to the two working electrodes with the counter and reference electrodes for each connected in the same manner as a normal “traditional” screen-printed sensor would be. This approach utilises the usually redundant back of the screen-printed sensor, converting this “dead-space” into a further electrochemical sensor which results in improvements in the analytical performance. In the use of the back-to-back design, the electrode area is consequently doubled with improvements in the analytical performance observed with the analytical sensitivity (gradient of a plot of peak height/analytical signal against concentration) doubling and the corresponding limit-of-detection being reduced. We also demonstrate that through intelligent electrode design, a quadruple in the observed analytical sensitivity can also be realised when double microband electrodes are used in the back-to-back configuration as long as they are placed sufficiently apart such that no diffusional interaction occurs. Such work is generic in nature and can be facilely applied to a plethora of screen-printed (and related) sensors utilising the commonly overlooked redundant back of the electrode providing facile improvements in the electroanalytical performance.The Analyst 09/2014; 139(21). DOI:10.1039/C4AN01501K · 3.91 Impact Factor