On the mechanism of the nitric oxide synthase-catalyzed conversion of N(ω)-hydroxy-L-arginine to citrulline and nitric oxide

From National Research Council Canada

Linkhttp://www.jbc.org/content/269/27/17776.abstract
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Name affiliation
  1. National Research Council of Canada. NRC Steacie Institute for Molecular Sciences
FormatText, Article
Journal titleThe Journal of Biological Chemistry
ISSN0021-9258
1083-351X
Volume269
Issue27
Pages17776–17779
Abstract
The mechanism of oxidation of N omega-hydroxyl-L-arginine (NHA) by the iron-dioxygen complex in nitric oxide synthase (NOS) is still uncertain. The uncertainty has not been helped by a lack of precision in the notation used to describe the oxidation states and electrical charges on the iron and oxygen in some of the suggested mechanisms. These problems of notation are addressed, and, in addition, a cyclic voltammetric measurement of the oxidation potential of NHA, namely +0.10 +/- 0.04 V versus normal hydrogen electrode, is used to argue that the sometimes postulated oxidation of NHA by the iron-dioxygen complex to form an intermediate radical cation, NHA.+, is very unlikely for thermodynamic reasons. Instead, it is suggested that this oxidation occurs by a thermodynamically favored abstraction of the hydrogen atom from the > C = NOH moiety of NHA to form an intermediate iminoxyl radical, > C = NO(.). A subsequent nucleophilic attack by the iron-hydroperoxide species formed by this H-atom abstraction on the carbon atom of the iminoxyl radical moiety leads to the production of nitric oxide (NO) and citrulline.
Publication date
PublisherAmerican Society for Biochemistry and Molecular Biology
LanguageEnglish
Peer reviewedYes
NPARC number21276835
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