@article{GoebelTalkeAhnertetal.2019, author = {G{\"o}bel, Gero and Talke, Anja and Ahnert, Uwe and Lisdat, Fred}, title = {Electrochemical Activity Determination of Catechol-O-methyl Transferase by Selective Dopamine Detection}, series = {ChemElectroChem}, volume = {6}, journal = {ChemElectroChem}, number = {17}, publisher = {Wiley}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-13900}, pages = {4533 -- 4540}, year = {2019}, abstract = {For the treatment of Parkinson's disease, as one of the most frequent diseases of the central nervous system, several key enzymes for dopamine metabolism [e. g. catechol-O-methyl transferase (COMT)] are drug targets. For an efficient and long-lasting treatment, the activity of this enzyme should be monitored. In this study, an electrochemical approach using differential pulse voltammetry (DPV) is introduced for the activity determination. The applied electrode material, fluorine-doped tin oxide (FTO), is characterized by a clear discrimination between substrate and product of COMT, a high stability of the dopamine signal during consecutive measurements, and a linear dependency on the dopamine concentration in the range of the maximum reaction rate of COMT. Despite these advantageous results, dopamine detection in the complete activity assay is influenced by each of the added essential assay components, even though none of the added components reveal a current signal at the FTO electrode itself. After adjusting the potential range and the assay composition, these effects can be circumvented. By following the dopamine concentrations during COMT action, it can be shown that the activity of COMT can be detected by using differential pulse voltammetry (DPV) at an FTO electrode and, by analyzing different COMT amounts, quantification can be demonstrated.}, language = {en} } @article{GoebelMuellerTalkeetal.2024, author = {G{\"o}bel, Gero and M{\"u}ller, Florian and Talke, Anja and Ahnert, Uwe and Lisdat, Fred}, title = {Qualitative and quantitative protease activity tests based on protein degradation in three-dimensional structures}, series = {Bioelectrochemistry}, volume = {160}, journal = {Bioelectrochemistry}, issn = {1567-5394}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-19294}, year = {2024}, abstract = {The pattern of the activity of proteases is related to distinct physiological states of living organisms. Often activity changes of a certain protease can be assigned to a specific disease. Hence, they are useful biomarkers and a simple and fast determination method of their activity could be a valuable tool for the efficient monitoring of numerous diseases. Here, two different methods for the qualitative and quantitative determination of protease activity are demonstrated using the model system of proteinase K. The first test system is based on a protein-modified and colored 3D silica structure that changes color when exposed to the enzyme. This method has also been used for the detection of matrix metallo-protease 2 (MMP2) with gelatine as protease substrate on the plates. The second detection system uses the decrease in the voltammetric signal of a cytochrome c/DNA multilayer electrode after incubation with a protease to quantitatively determine its proteolytic activity. While activities down to 0.15 U/ml can be detected with the first method, the second one provides detection limits of about 0.03 U/ml (for proteinase K.) The functionality of both systems can be demonstrated and ways for further enhancement of sensitivity have been elucidated.}, language = {en} }