TY - JOUR A1 - Scheller, Frieder W. A1 - Yarman, Aysu T1 - Bio vs. Mimetika in der Bioanalytik T1 - Bio vs. Mimetics in Bioanalysis: An Editorial BT - ein Editorial JF - Biochemie und analytische Biochemie N2 - Natürliche Evolution hat geschaffenBiopolymereauf der Basis von Aminosäuren undNukleotidezeigt hohe chemische Selektivität und katalytische Kraft. Die molekulare Erkennung durch Antikörper und die katalytische Umwandlung der Substratmoleküle durch Enzyme findet in sogenannten Paratopen oder katalytischen Zentren des Makromoleküls statt, die typischerweise 10-15 Aminosäuren umfassen. Die konzertierte Wechselwirkung zwischen den Reaktionspartnern führt zu Affinitäten bis zu nanomolaren Konzentrationen für die Antigenbindung und nähert sich einer Million Umsätze pro Sekunde anEnzym-katalysierte Reaktionen. N2 - Natural evolution has created biopolymers on the basis of amino acids and nucleotides showing high chemical selectivity and catalytic power. Molecular recognition by antibodies and catalytic conversion of the substrate molecules by enzymes take place in so called paratopes or catalytic centres of the macromolecule which comprise typically 10-15 amino acids. The concerted interaction between the reaction partners result in affinities down to nanomolar concentrations for the antigen binding and approaches one million turnovers per second in enzyme-catalyzed reactions. Nucleic acids bind complimentary single stranded nucleic acids by base pairing (hybridisation) with nanomolar affinities but also interact highly specific with proteins, e.g. transcription factors, and lowmolecular weight molecules and even with ions. Biomimetic binders and catalysts have been generated using “evolution in the test tube” of non-natural nucleotides or total chemical synthesis of (molecularly imprinted) polymers in order to substitute the biological pendants in bioanalysis. Y1 - 2015 SN - 2161-1009 VL - 4 IS - 2 ER - TY - JOUR A1 - Yarman, Aysu A1 - Dechtrirat, Decha A1 - Bosserdt, Maria A1 - Jetzschmann, Katharina J. A1 - Gajovic-Eichelmann, Nenad A1 - Scheller, Frieder W. T1 - Cytochrome c-derived hybrid systems based on moleculary imprinted polymers JF - Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis N2 - Hybrid architectures which combine a MIP with an immobilized affinity ligand or a biocatalyst sum up the advantages of both components. In this paper, hybrid architectures combining a layer of a molecularly imprinted electropolymer with a mini-enzyme or a self-assembled monolayer will be presented. (i) Microperoxidase-11 (MP-11) catalyzed oxidation of the drug aminopyrine on a product-imprinted sublayer: The peroxide dependent conversion of the analyte aminopyrine takes place in the MP-11 containing layer on top of a product-imprinted electropolymer on the indicator electrode. The hierarchical architecture resulted in the elimination of interfering signals for ascorbic acid and uric acid. An advantage of the new hierarchical structure is the separation of MIP formation by electropolymerization and immobilization of the catalyst. In this way it was for the first time possible to integrate an enzyme with a MIP layer in a sensor configuration. This combination has the potential to be transferred to other enzymes, e.g. P450, opening the way to clinically important analytes. (ii) Epitope-imprinted poly-scopoletin layer for binding of the C-terminal peptide and cytochrome c (Cyt c): The MIP binds both the target peptide and the parent protein almost eight times stronger than the non-imprinted polymer with affinities in the lower micromolar range. Exchange of only one amino acid in the peptide decreases the binding by a factor of five. (iii) MUA-poly-scopoletin MIP for cytochrome c: Cyt c bound to the MIP covered gold electrode exhibits direct electron transfer with a redox potential and rate constant typical for the native protein. The MIP cover layer suppresses the displacement of the target protein by BSA or myoglobin. The combination of protein imprinted polymers with an efficient electron transfer is a new concept for characterizing electroactive proteins such as Cyt c. The competition with other proteins shows that the MIP binds its target Cyt c preferentially and that molecular shape and the charge of protein determine the binding of interfering proteins. KW - Molecularly imprinted polymers KW - Microperoxidase-11 KW - Cytochrome c KW - Catalytically active MIPs KW - Epitope imprinting KW - Monoclonal MIPs Y1 - 2015 U6 - https://doi.org/10.1002/elan.201400592 SN - 1040-0397 SN - 1521-4109 VL - 27 IS - 3 SP - 573 EP - 586 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Peng, Lei A1 - Utesch, Tillmann A1 - Yarman, Aysu A1 - Jeoung, Jae-Hun A1 - Steinborn, Silke A1 - Dobbek, Holger A1 - Mroginski, Maria Andrea A1 - Tanne, Johannes A1 - Wollenberger, Ursula A1 - Scheller, Frieder W. T1 - Surface-Tuned Electron Transfer and Electrocatalysis of Hexameric Tyrosine-Coordinated Heme Protein JF - Chemistry - a European journal N2 - Molecular modeling, electrochemical methods, and quartz crystal microbalance were used to characterize immobilized hexameric tyrosine-coordinated heme protein (HTHP) on bare carbon or on gold electrodes modified with positively and negatively charged self-assembled monolayers (SAMs), respectively. HTHP binds to the positively charged surface but no direct electron transfer (DET) is found due to the long distance of the active sites from the electrode surfaces. At carboxyl-terminated surfaces, the neutrally charged bottom of HTHP can bind to the SAM. For this "disc" orientation all six hemes are close to the electrode and their direct electron transfer should be efficient. HTHP on all negatively charged SAMs showed a quasi-reversible redox behavior with rate constant k(s) values between 0.93 and 2.86 s(-1) and apparent formal potentials E-app(0)' between -131.1 and -249.1 mV. On the MUA/MU-modified electrode, the maximum surface concentration corresponds to a complete monolayer of the hexameric HTHP in the disc orientation. HTHP electrostatically immobilized on negatively charged SAMs shows electrocatalysis of peroxide reduction and enzymatic oxidation of NADH. KW - electrochemistry KW - electron transfer KW - heme proteins KW - molecular modeling KW - monolayers Y1 - 2015 U6 - https://doi.org/10.1002/chem.201405932 SN - 0947-6539 SN - 1521-3765 VL - 21 IS - 20 SP - 7596 EP - 7602 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Jetzschmann, Katharina J. A1 - Jagerszki, Gyula A1 - Dechtrirat, Decha A1 - Yarman, Aysu A1 - Gajovic-Eichelmann, Nenad A1 - Gilsing, Hans-Detlev A1 - Schulz, Burkhard A1 - Gyurcsanyi, Robert E. A1 - Scheller, Frieder W. T1 - Vectorially Imprinted Hybrid Nanofilm for Acetylcholinesterase Recognition JF - Advanced functional materials N2 - Effective recognition of enzymatically active tetrameric acetylcholinesterase (AChE) is accomplished by a hybrid nanofilm composed of a propidium-terminated self-assembled monolayer (Prop-SAM) which binds AChE via its peripheral anionic site (PAS) and an ultrathin electrosynthesized molecularly imprinted polymer (MIP) cover layer of a novel carboxylate-modified derivative of 3,4-propylenedioxythiophene. The rebinding of the AChE to the MIP/Prop-SAM nanofilm covered electrode is detected by measuring in situ the enzymatic activity. The oxidative current of the released thiocholine is dependent on the AChE concentration from approximate to 0.04 x 10(-6) to 0.4 x 10(-6)m. An imprinting factor of 9.9 is obtained for the hybrid MIP, which is among the best values reported for protein imprinting. The dissociation constant characterizing the strength of the MIP-AChE binding is 4.2 x 10(-7)m indicating the dominant role of the PAS-Prop-SAM interaction, while the benefit of the MIP nanofilm covering the Prop-SAM layer is the effective suppression of the cross-reactivity toward competing proteins as compared with the Prop-SAM. The threefold selectivity gain provided by i) the shape-specific MIP filter, ii) the propidium-SAM, iii) signal generation only by the AChE bound to the nanofilm shows promise for assessing AChE activity levels in cerebrospinal fluid. KW - acetylcholinesterase KW - biomimetic sensors KW - molecularly imprinted electropolymers KW - peripheral anionic site KW - propidium Y1 - 2015 U6 - https://doi.org/10.1002/adfm.201501900 SN - 1616-301X SN - 1616-3028 VL - 25 IS - 32 SP - 5178 EP - 5183 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Tanne, Johannes A1 - Jeoung, Jae-Hun A1 - Peng, Lei A1 - Yarman, Aysu A1 - Dietzel, Birgit A1 - Schulz, Burkhard A1 - Schad, Daniel A1 - Dobbek, Holger A1 - Wollenberger, Ursula A1 - Bier, Frank Fabian A1 - Scheller, Frieder W. T1 - Direct Electron Transfer and Bioelectrocatalysis by a Hexameric, Heme Protein at Nanostructured Electrodes JF - Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis N2 - A nanohybrid consisting of poly(3-aminobenzenesulfonic acid-co-aniline) and multiwalled carbon nanotubes [MWCNT-P(ABS-A)]) on a gold electrode was used to immobilize the hexameric tyrosine-coordinated heme protein (HTHP). The enzyme showed direct electron transfer between the heme group of the protein and the nanostructured surface. Desorption of the noncovalently bound heme from the protein could be excluded by control measurements with adsorbed hemin on aminohexanthiol-modified electrodes. The nanostructuring and the optimised charge characteristics resulted in a higher protein coverage as compared with MUA/MU modified electrodes. The adsorbed enzyme shows catalytic activity for the cathodic H2O2 reduction and oxidation of NADH. KW - HTHP KW - Nanohybrid KW - Poylaniline KW - Multiwalled carbon nanotube Y1 - 2015 U6 - https://doi.org/10.1002/elan.201500231 SN - 1040-0397 SN - 1521-4109 VL - 27 IS - 10 SP - 2262 EP - 2267 PB - Wiley-VCH CY - Weinheim ER -