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Published August 17, 2005 | Accepted Version + Supplemental Material
Journal Article Open

Redox Couples of Inducible Nitric Oxide Synthase

Abstract

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 Fe^(III/II) and Fe^(II/I) couples at −191 and −1049 mV (vs Ag/AgCl). Imidazole and carbon monoxide in solution shift the Fe^(III/II) potential by +20 and +62 mV, while the addition of dioxygen results in large catalytic waves at the onset of Fe^(III) reduction. Voltammetry at higher scan rates (with pH variations) reveals that the Fe^(III/II) cathodic peak can be resolved into two components, which are attributable to Fe^(III/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.

Additional Information

© 2005 American Chemical Society. Received March 29, 2005. Publication Date (Web): July 20, 2005. Supported by NSERC (Canada) (A.K.U.), HHMI (A.K.U.), NIH (DK19038; GM070868), the Packard Foundation (M.G.H.), the Ellison Medical Foundation (Senior Scholar Award in Aging to H.B.G.), and the Parsons Foundation (W.B.B.); S. Luzzi (Berkeley) assisted with protein expression and purification.

Attached Files

Accepted Version - nihms63657.pdf

Supplemental Material - ja0520114si20050706_032608.pdf

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Created:
August 19, 2023
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October 25, 2023