Graphite electrodes modified with Neurospora crassa cellobiose dehydrogenase: comparative electrochemical characterization under direct and mediated electron transfer.
The electrochemical characterization of a class II cellobiose dehydrogenase (CDH), from the ascomycete fungus Neurospora crassa, adsorbed on graphite (G), was performed in regard to direct (DET) and mediated electron transfer (MET). The effects of the applied potential, mediator (1,4 benzoquinone) concentration and flow carrier pH on the amperometric response of the G/CDH modified electrodes were investigated under flow conditions. From the calibration curves, recorded at two pH values (5.2 and 7.0) for nine different sugars, the kinetic and the analytical parameters were evaluated under DET and MET operation modes. These results together with those obtained from long term operational stability measurements showed that: (i) for all nine investigated sugars the sensitivity was higher for MET than for DET and for pH 5.2 compared to pH 7.0; (ii) irrespective of DET or MET operation mode, the sensitivity of the new enzyme towards the investigated sugars decreased in the following sequence: cellobiose>lactose>(cellotriose≈cellopentaose) >>(maltotriose≈maltotetraose≈maltopentaose)>(maltose≈glucose); (iii) for all tested substrates, the apparent CDH affinity was roughly higher in DET than in MET operation mode.
Department of Physical Chemistry, Babeş-Bolyai University, Arany Janos 11, 400028 Cluj-Napoca, Romania.
Gabor
G
Kovacs
Roberto
R
Ortiz
Vasile
V
Coman
Wolfgang
W
Harreither
Ionel Catalin
IC
Popescu
Roland
R
Ludwig
Lo
L
Gorton
D000327:Adsorption; D055162:Biocatalysis; D015374:Biosensing Techniques; D002237:Carbohydrate Dehydrogenases / Q000737:chemistry* / Q000378:metabolism*; D002241:Carbohydrates / Q000032:analysis / Q000737:chemistry; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D004579:Electron Transport; D004795:Enzyme Stability; D006108:Graphite / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009492:Neurospora crassa / Q000201:enzymology*; D013499:Surface Properties
D002241:Carbohydrates; D006108:Graphite; D002237:Carbohydrate Dehydrogenases; C019859:cellobiose-quinone oxidoreductase