Mediated, anaerobic voltammetry of sulfite oxidase.
The anaerobic voltammetry of the Mo/Fe enzyme, sulfite oxidase (SO), is described for the mediators cytochrome c, [Ru(NH3)6]3+/2+, TMPD+/0, and [Co(bpy)3]3+/2+. Theory derived for steady-state voltammetric catalysis correctly predicts the observed concentration and scan-rate dependencies of the catalytic waves. The instances for which existing ECcat theories may be applied to two catalytic reactions coupled to an interfacial charge transfer are considered. The biomolecular rate constant for the reaction of [Co(bpy)3]3+ with reduced SO is calculated and determined to be approximately 5 X 10(4) L.mol-1.s-1. The appearance of catalytic prepeaks at low sulfite concentrations is noted and the shape of corresponding i/t curves from chronoamperometry is examined. The analytical implications of the novel time dependence of the catalytic current under these conditions are discussed.
Coury
L A
LA
Venable and Kenan Laboratories of Chemistry, University of North Carolina, Chapel Hill 27599-3290.
Oliver
B N
BN
Egekeze
J O
JO
Sosnoff
C S
CS
Brumfield
J C
JC
Buck
R P
RP
Murray
R W
RW
D000693:Anaerobiosis; D003579:Cytochrome Reductases / Q000032:analysis*; D004563:Electrochemistry; D007202:Indicators and Reagents; D050902:Sulfite Dehydrogenase
D007202:Indicators and Reagents; D003579:Cytochrome Reductases; D050902:Sulfite Dehydrogenase