Direct catalytic electrochemistry of sulfite dehydrogenase: Mechanistic insights and contrasts with related Mo enzymes

Rapson, Trevor D., Kappler, Ulrike and Bernhardt, Paul V. (2008) Direct catalytic electrochemistry of sulfite dehydrogenase: Mechanistic insights and contrasts with related Mo enzymes. Biochimica Et Biophysica Acta-bioenergetics, 1777 10: 1319-1325. doi:10.1016/j.bbabio.2008.06.005


Author Rapson, Trevor D.
Kappler, Ulrike
Bernhardt, Paul V.
Title Direct catalytic electrochemistry of sulfite dehydrogenase: Mechanistic insights and contrasts with related Mo enzymes
Journal name Biochimica Et Biophysica Acta-bioenergetics   Check publisher's open access policy
ISSN 0005-2728
Publication date 2008-06-13
Year available 2008
Sub-type Article (original research)
DOI 10.1016/j.bbabio.2008.06.005
Volume 1777
Issue 10
Start page 1319
End page 1325
Total pages 7
Place of publication Netherlands
Publisher Elsevier BV
Collection year 2009
Language eng
Subject C1
060107 Enzymes
060104 Cell Metabolism
920106 Endocrine Organs and Diseases (excl. Diabetes)
920110 Inherited Diseases (incl. Gene Therapy)
Formatted abstract
Under hydrodynamic electrochemical conditions with slow cyclic voltammetry sweep rates we have been able to probe catalytic events at the molybdenum active site of sulfite dehydrogenase (SDH) from Starkeya novella adsorbed on an edge plane graphite electrode within a polylysine film. The electrochemically driven catalytic behaviour of SDH mirrors that seen in solution assays suggesting that the adsorbed enzyme retains its native activity. However, at high sulfite concentrations, the voltammetric waveform transforms from the expected sigmoidal profile to a peak-shaped response, similar to that reported for the molybdenum enzymes DMSO reductase and nitrate reductase (NarGHI and NapAB) where a redox reaction at the active site has been associated with a switch to lower activity at high overpotentials. This is the first time a similar phenomenon has been observed in a Mo-containing oxidase/dehydrogenase, which raises a number of interesting mechanistic problems. The potential at which the activity of SDH becomes attenuated only emerges at saturating substrate conditions and occurs at a potential (ca. + 320mV vs NHE) well removed from any known redox couple in the enzyme. These results cannot be explained by the same mechanism adopted for DMSO reductase and nitrate reductase catalysis.
Keyword molybdenum
enzyme
electrochemistry
Q-Index Code C1
Q-Index Status Confirmed Code

 
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Created: Wed, 25 Feb 2009, 12:55:00 EST by Jennifer Falknau on behalf of Faculty of Science