@article{SchellerYarman2015, author = {Scheller, Frieder W. and Yarman, Aysu}, title = {Bio vs. Mimetika in der Bioanalytik}, series = {Biochemie und analytische Biochemie}, volume = {4}, journal = {Biochemie und analytische Biochemie}, number = {2}, issn = {2161-1009}, pages = {2}, year = {2015}, abstract = {Nat{\"u}rliche Evolution hat geschaffenBiopolymereauf der Basis von Aminos{\"a}uren undNukleotidezeigt hohe chemische Selektivit{\"a}t und katalytische Kraft. Die molekulare Erkennung durch Antik{\"o}rper und die katalytische Umwandlung der Substratmolek{\"u}le durch Enzyme findet in sogenannten Paratopen oder katalytischen Zentren des Makromolek{\"u}ls statt, die typischerweise 10-15 Aminos{\"a}uren umfassen. Die konzertierte Wechselwirkung zwischen den Reaktionspartnern f{\"u}hrt zu Affinit{\"a}ten bis zu nanomolaren Konzentrationen f{\"u}r die Antigenbindung und n{\"a}hert sich einer Million Ums{\"a}tze pro Sekunde anEnzym-katalysierte Reaktionen.}, language = {de} } @article{PengUteschYarmanetal.2015, author = {Peng, Lei and Utesch, Tillmann and Yarman, Aysu and Jeoung, Jae-Hun and Steinborn, Silke and Dobbek, Holger and Mroginski, Maria Andrea and Tanne, Johannes and Wollenberger, Ursula and Scheller, Frieder W.}, title = {Surface-Tuned Electron Transfer and Electrocatalysis of Hexameric Tyrosine-Coordinated Heme Protein}, series = {Chemistry - a European journal}, volume = {21}, journal = {Chemistry - a European journal}, number = {20}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.201405932}, pages = {7596 -- 7602}, year = {2015}, abstract = {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.}, language = {en} } @article{SpricigoLeimkuehlerGortonetal.2015, author = {Spricigo, Roberto and Leimk{\"u}hler, Silke and Gorton, Lo and Scheller, Frieder W. and Wollenberger, Ursula}, title = {The Electrically Wired Molybdenum Domain of Human Sulfite Oxidase is Bioelectrocatalytically Active}, series = {European journal of inorganic chemistry : a journal of ChemPubSoc Europe}, journal = {European journal of inorganic chemistry : a journal of ChemPubSoc Europe}, number = {21}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1434-1948}, doi = {10.1002/ejic.201500034}, pages = {3526 -- 3531}, year = {2015}, abstract = {We report electron transfer between the catalytic molybdenum cofactor (Moco) domain of human sulfite oxidase (hSO) and electrodes through a poly(vinylpyridine)-bound [osmium(N,N'-methyl-2,2'-biimidazole)(3)](2+/3+) complex as the electron-transfer mediator. The biocatalyst was immobilized in this low-potential redox polymer on a carbon electrode. Upon the addition of sulfite to the immobilized separate Moco domain, the generation of a significant catalytic current demonstrated that the catalytic center is effectively wired and active. The bioelectrocatalytic current of the wired separate catalytic domain reached 25\% of the signal of the wired full molybdoheme enzyme hSO, in which the heme b(5) is involved in the electron-transfer pathway. This is the first report on a catalytically active wired molybdenum cofactor domain. The formal potential of this electrochemical mediator is between the potentials of the two cofactors of hSO, and as hSO can occupy several conformations in the polymer matrix, it is imaginable that electron transfer from the catalytic site to the electrode through the osmium center occurs for the hSO molecules in which the Moco domain is sufficiently accessible. The observation of catalytic oxidation currents at low potentials is favorable for applications in bioelectronic devices.}, language = {en} } @article{JetzschmannJagerszkiDechtriratetal.2015, author = {Jetzschmann, Katharina J. and Jagerszki, Gyula and Dechtrirat, Decha and Yarman, Aysu and Gajovic-Eichelmann, Nenad and Gilsing, Hans-Detlev and Schulz, Burkhard and Gyurcsanyi, Robert E. and Scheller, Frieder W.}, title = {Vectorially Imprinted Hybrid Nanofilm for Acetylcholinesterase Recognition}, series = {Advanced functional materials}, volume = {25}, journal = {Advanced functional materials}, number = {32}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1616-301X}, doi = {10.1002/adfm.201501900}, pages = {5178 -- 5183}, year = {2015}, abstract = {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.}, language = {en} } @article{TanneJeoungPengetal.2015, author = {Tanne, Johannes and Jeoung, Jae-Hun and Peng, Lei and Yarman, Aysu and Dietzel, Birgit and Schulz, Burkhard and Schad, Daniel and Dobbek, Holger and Wollenberger, Ursula and Bier, Frank Fabian and Scheller, Frieder W.}, title = {Direct Electron Transfer and Bioelectrocatalysis by a Hexameric, Heme Protein at Nanostructured Electrodes}, series = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, volume = {27}, journal = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, number = {10}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1040-0397}, doi = {10.1002/elan.201500231}, pages = {2262 -- 2267}, year = {2015}, abstract = {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.}, language = {en} }