Nitric oxide and iron proteins

Nitric oxide interactions with iron are the most important biological react ions in which NO participates. Reversible binding to ferrous haem iron is r esponsible for the observed activation of guanylate cyclase and inhibition of cytochrome oxidase. Unlike carbon monoxide or oxygen, NO can also bind r eversibly to ferric iron. The latter reaction is responsible for the inhibi tion of catalase by NO. NO reacts with the oxygen adduct of ferrous haem pr oteins (e.g. oxyhaemoglobin) to generate nitrate and ferric haem; this reac tion is responsible for the majority of NO metabolism in the vasculature, N O can also interact with iron-sulphur enzymes (e.g. aconitase, NADH dehydro genase), This review describes the underlying kinetics, thermodynamics, mec hanisms and biological role of the interactions of NO with iron species (pr otein and nonprotein bound). The possible significance of iron reactions wi th reactive NO metabolites, in particular peroxynitrite and nitroxyl anion, is also discussed. (C) 1999 Elsevier Science B.V. All rights reserved.