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  - 
TY  - JOUR
A1  - Sezer, Murat
A1  - Spricigo, Roberto
A1  - Utesch, Tillmann
A1  - Millo, Diego
A1  - Leimkühler, Silke
A1  - Mroginski, Maria A.
A1  - Wollenberger, Ursula
A1  - Hildebrandt, Peter
A1  - Weidinger, Inez M.
T1  - Redox properties and catalytic activity of surface-bound human sulfite oxidase studied by a combined surface enhanced resonance Raman spectroscopic and electrochemical approach
N2  - Human sulfite oxidase (hSO) was immobilised on SAM-coated silver electrodes under preservation of the native heme pocket structure of the cytochrome b5 (Cyt b5) domain and the functionality of the enzyme. The redox properties and catalytic activity of the entire enzyme were studied by surface enhanced resonance Raman (SERR) spectroscopy and cyclic voltammetry (CV) and compared to the isolated heme domain when possible. It is shown that heterogeneous electron transfer and catalytic activity of hSO sensitively depend on the local environment of the enzyme. Increasing the ionic strength of the buffer solution leads to an increase of the heterogeneous electron transfer rate from 17 s(-1) to 440 s(- 1) for hSO as determined by SERR spectroscopy. CV measurements demonstrate an increase of the apparent turnover rate for the immobilised hSO from 0.85 s(-1) in 100 mM buffer to 5.26 s(-1) in 750 mM buffer. We suggest that both effects originate from the increased mobility of the surface-bound enzyme with increasing ionic strength. In agreement with surface potential calculations we propose that at high ionic strength the enzyme is immobilised via the dimerisation domain to the SAM surface. The flexible loop region connecting the Moco and the Cyt b5 domain allows alternating contact with the Moco interaction site and the SAM surface, thereby promoting the sequential intramolecular and heterogeneous electron transfer from Moco via Cyt b5 to the electrode. At lower ionic strength, the contact time of the Cyt b5 domain with the SAM surface is longer, corresponding to a slower overall electron transfer process.
Y1  - 2010
UR  - http://www.rsc.org/Publishing/Journals/CP/index.asp
U6  - https://doi.org/10.1039/B927226g
SN  - 1463-9076
ER  -