Redox couples of inducible nitric oxide synthase.
We report direct electrochemistry of the iNOS heme domain in a DDAB film on the surface of a basal plane graphite electrode. Cyclic voltammetry reveals FeIII/II and FeII/I couples at -191 and -1049 mV (vs Ag/AgCl). Imidazole and carbon monoxide in solution shift the FeIII/II potential by +20 and +62 mV, while the addition of dioxygen results in large catalytic waves at the onset of FeIII reduction. Voltammetry at higher scan rates (with pH variations) reveals that the FeIII/II cathodic peak can be resolved into two components, which are attributable to FeIII/II couples of five- and six-coordinate hemes. Digital simulation of our experimental data implicates water dissociation from the heme as a gating mechanism for ET in iNOS.
Udit
Andrew K
AK
Department of Chemistry, Occidental College, Los Angeles, California 90041, USA.
Belliston-Bittner
Wendy
W
Glazer
Edith C
EC
Nguyen
Yen Hoang Le
YH
Gillan
James M
JM
Hill
Michael G
MG
Marletta
Michael A
MA
Goodin
David B
DB
Gray
Harry B
HB
D000818:Animals; D004579:Electron Transport; D006801:Humans; D007501:Iron / Q000737:chemistry*; D010084:Oxidation-Reduction
D007501:Iron