title: Redox potential determines the reaction mechanism of HNO donors with Mn and Fe porphyrins: defining the better traps.
abstract: Azanone ((1)HNO, nitroxyl) is a highly reactive molecule with interesting chemical and biological properties. Like nitric oxide (NO), its main biologically related targets are oxygen, thiols, and metalloproteins, particularly heme proteins. As HNO dimerizes with a rate constant between 10(6) and 10(7) M(-1) s(-1), reactive studies are performed using donors, which are compounds that spontaneously release HNO in solution. In the present work, we studied the reaction mechanism and kinetics of two azanone donors Angelís Salt and toluene sulfohydroxamic acid (TSHA) with eight different Mn porphyrins as trapping agents. These porphyrins differ in their total peripheral charge (positively or negatively charged) and in their Mn(III)/Mn(II) reduction potential, showing for each case positive (oxidizing) and negative (reducing) values. Our results show that the reduction potential determines the azanone donor reaction mechanism. While oxidizing porphyrins accelerate decomposition of the donor, reducing porphyrins react with free HNO. Our results also shed light into the donor decomposition mechanism using ab initio methods and provide a thorough analysis of which MnP are the best candidates for azanone trapping and quantification experiments.
authors.affiliation: Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, INQUIMAE-CONICET and ‡Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria , Pab. II (1428), Buenos Aires, Argentina.
authors.forename: Lucía
authors.initials: L
authors.lastname: Alvarez
authors.forename: Sebastián A
authors.initials: SA
authors.lastname: Suarez
authors.forename: Damian E
authors.initials: DE
authors.lastname: Bikiel
authors.forename: Julio S
authors.initials: JS
authors.lastname: Reboucas
authors.forename: Ines
authors.initials: I
authors.lastname: Batinić-Haberle
authors.forename: Marcelo A
authors.initials: MA
authors.lastname: Martí
authors.forename: Fabio
authors.initials: F
authors.lastname: Doctorovich
mesh_terms: D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D008345:Manganese / Q000737:chemistry*; D009589:Nitrogen Oxides / Q000737:chemistry*; D010084:Oxidation-Reduction; D011166:Porphyrins / Q000737:chemistry*
chemical_list: D009589:Nitrogen Oxides; D011166:Porphyrins; D008345:Manganese; D007501:Iron; C039900:nitroxyl