Fast Nitroxyl Trapping by Ferric Porphyrins

S. BARI; M. MARTI; V. AMOREBIETA; D.A. ESTRIN; F. DOCTOROVICH

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2003 vol. 125 p. 15272 - 15273

0002-7863

Nitroxyl anion (NO-), the elusive one- electron reduction productof nitric oxide (NO), is currently being considered as a product ofthe enzyme nitric oxide synthase (NOS).1 It is also biosynthesizedfrom N-hydroxy-L-arginine under oxidative stress2 or nonenzymati-cally from the reaction of S-nitrosothiols with thiols.3 Nevertheless,it has been recently demonstrated that the direct one-electronreduction of NO is thermodynamically unfavored under physio-logical conditions,4 where the conjugated weak acid nitroxyl (HNO)is the predominant species.5 The anion or its conjugated acid arecapable of reacting with heme or non-heme iron6 and with thiolresidues, respectively, pointing to hemeproteins as relevant bio-chemical targets.7 However, no studies have been reported on thereactions of heme model systems with NO-/HNO. In this workwe report for the first time an investigation of the reactions of NO-/HNO with ferriheme model systems. These reactions not only shedlight on the putative mechanisms operating under physiologicalconditions but could also provide a powerful tool for the discrimi-nation of NO and NO-/HNO biological effects by selectivetrapping.