TY  - JOUR
A1  - Spricigo, Roberto
A1  - Leimkühler, Silke
A1  - Gorton, Lo
A1  - Scheller, Frieder W.
A1  - Wollenberger, Ursula
T1  - The Electrically Wired Molybdenum Domain of Human Sulfite Oxidase is Bioelectrocatalytically Active
JF  - European journal of inorganic chemistry : a journal of ChemPubSoc Europe
N2  - 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.
KW  - Metalloenzymes
KW  - Enzyme catalysis
KW  - Immobilization
KW  - Osmium
Y1  - 2015
U6  - https://doi.org/10.1002/ejic.201500034
SN  - 1434-1948
SN  - 1099-0682
IS  - 21
SP  - 3526
EP  - 3531
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Kielb, Patrycja
A1  - Sezer, Murat
A1  - Katz, Sagie
A1  - Lopez, Francesca
A1  - Schulz, Christopher
A1  - Gorton, Lo
A1  - Ludwig, Roland
A1  - Wollenberger, Ursula
A1  - Zebger, Ingo
A1  - Weidinger, Inez M.
T1  - Spectroscopic Observation of Calcium-Induced Reorientation of Cellobiose Dehydrogenase Immobilized on Electrodes and its Effect on Electrocatalytic Activity
JF  - ChemPhysChem : a European journal of chemical physics and physical chemistry
N2  - Cellobiose dehydrogenase catalyzes the oxidation of various carbohydrates and is considered as a possible anode catalyst in biofuel cells. It has been shown that the catalytic performance of this enzyme immobilized on electrodes can be increased by presence of calcium ions. To get insight into the Ca2+-induced changes in the immobilized enzyme we employ surface-enhanced vibrational (SERR and SEIRA) spectroscopy together with electrochemistry. Upon addition of Ca2+ ions electrochemical measurements show a shift of the catalytic turnover signal to more negative potentials while SERR measurements reveal an offset between the potential of heme reduction and catalytic current. Comparing SERR and SEIRA data we propose that binding of Ca2+ to the heme induces protein reorientation in a way that the electron transfer pathway of the catalytic FAD center to the electrode can bypass the heme cofactor, resulting in catalytic activity at more negative potentials.
KW  - cellobiose dehydrogenase
KW  - electron transfer
KW  - enzyme catalysis
KW  - spectroelectrochemistry
KW  - surface-enhanced vibrational spectroscopy
Y1  - 2015
U6  - https://doi.org/10.1002/cphc.201500112
SN  - 1439-4235
SN  - 1439-7641
VL  - 16
IS  - 9
SP  - 1960
EP  - 1968
PB  - Wiley-VCH
CY  - Weinheim
ER  -