TY  - JOUR
A1  - Shumyantseva, V. V.
A1  - Ivanov, Y. D.
A1  - Bistolas, Nikitas
A1  - Scheller, Frieder W.
A1  - Archakov, Alexander I.
A1  - Wollenberger, Ursula
T1  - Direct electron transfer of cytochrome P450 2B4 at electrodes modified with non-ionic detergent and colloidal clay nanoparticles
N2  - A method for construction of biosensors with membranous cytochrome P450 isoenzymes was developed based on clay/ detergent/protein mixed films. Thin films of sodium montmorillonite colloid with incorporated cytochrome P450 2134 (CYP2B4) with nonionic detergent were prepared on glassy carbon electrodes. The modified electrodes were electrochemically characterized, and bio-electrocatalytic reactions were followed. CYP2B4 can be reduced fast on clay- modified glassy carbon electrodes in the presence of the nonionic detergent Tween 80. In anaerobic solutions, reversible oxidation and reduction is obtained with a formal potential between -0.292 and - 0.305 V vs Ag/AgCl 1 M KCl depending on the preparation of the biosensor. In air-saturated solution, bio-electrocatalytic reduction currents can be obtained with the CYP2B4-modified electrode on addition of typical substrates such as aminopyrine and benzphetamine. This reaction was suppressed when methyrapone, an inhibitor of P450 reactions, was present. Measurement of product formation also indicates the bioelectrocatialysis by CYP2B4
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Loew, Noya
A1  - Scheller, Frieder W.
A1  - Wollenberger, Ursula
T1  - Characterization of self-assembling of glucose dehydrogenase in mono- and multilayers on gold electrodes
N2  - Glucose dehydrogenase (GDH) was assembled electrostatically onto QCM-gold electrodes by their sequential deposition with anionic polyelectrolytes such as PSS and PASA. For the layer-by-layer arrangements both the microgravimetric and the electrochemical sensor signal were followed. Increasing amounts of GDH were deposited by stepwise formation of alternating layers of GDH and PSS or PASA. The mass increase was about 1.88 mug/cm(2) for one GDH/ PASA bilayer and 2.4 mug/cm(2) for a GDH/PSS bilayer. The addition of phenolic compounds resulted in an oxidation current, which could be catalytically increased by the GDH catalysed reaction in the presence of glucose. The system functions as glucose sensor when quinones are present in nonlimiting amount. The amperometric response was already diffusion limited when a single layer of GDH was adsorbed. The sensor sensitivity increased by a factor of 10 when MSA was used instead of MUA as initial electrode modifier
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Kulys, J.
A1  - Krikstopaitis, K.
A1  - Scheller, Frieder W.
A1  - Wollenberger, Ursula
T1  - Electrochemical parameters of phenoxazine derivatives in solution and at monolayer-modified gold electrodes
N2  - Electrochemical properties of beta-(10-phenoxazinyl) propylamine (APPX) and beta-(10-phenoxazinyl) propionic acid (PPX) have been studied in solution, and in immobilized state on gold electrodes modified with monolayers of cystamine and mercaptoundecanoic acid. A reversible diffusion-controlled process of APPX and PPX was observed at a bare gold electrode. The electrochemical conversion of both compounds at modified gold electrodes was a quasireversible diffusion-controlled process. The redox potential of immobilized APPX (443 mV) was similar to the potential in solution, while the value of the immobilized PPX was 131 mV higher than in solution. The immobilized mediators were electrocatalytically active in the fungal peroxidase-catalyzed hydrogen peroxide reduction
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Bistolas, Nikitas
A1  - Christenson, A.
A1  - Ruzgas, T.
A1  - Jung, Christiane
A1  - Scheller, Frieder W.
A1  - Wollenberger, Ursula
T1  - Spectroelectrochemistry of cytochrome P450cam
N2  - The spectroelectrochemistry of camphor-bound cytochrome P450cam (P450cam) using gold electrodes is described. The electrodes were modified with either 4,4'-dithiodipyridin or sodium dithionite. Electrolysis of P450cam was carried out when the enzyme was in solution, while at the same time UV visible absorption spectra were recorded. Reversible oxidation and reduction could be observed with both 4,4'-dithiodipyridin and dithionite modified electrodes. A formal potential (E-0') of -373 mV vs Ag/AgCl 1 M KCl was determined. The spectra of P450cam complexed with either carbon monoxide or metyrapone, both being inhibitors of P450 catalysis, clearly indicated that the protein retained its native state in the electrochemical cell during electrolysis. (C) 2003 Elsevier Inc. All rights reserved
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Wollenberger, Ursula
A1  - Bistolas, Nikitas
A1  - Jung, Christiane
A1  - Shumyantseva, V. V.
A1  - Ruzgas, T.
A1  - Scheller, Frieder W.
T1  - Elektroden-Design für elektronische Wechselwirkung mit Monooxygenasen
Y1  - 2004
SN  - 3-8047-2132-x
ER  - 
TY  - JOUR
A1  - Kröning, Steffen
A1  - Scheller, Frieder W.
A1  - Wollenberger, Ursula
A1  - Lisdat, Fred
T1  - Myoglobin-Clay Electrode for Nitric Oxide (NO) Detection in Solution
Y1  - 2004
ER  -