NO2(-)-mediated nitrosylation of ferrous microperoxidase-11.
Microperoxidase-11 (MP11) is an undecapeptide derived from horse heart cytochrome c (cyt c) and characterized by a covalently-linked solvent-exposed heme group. Here, kinetics of the NO2(-)-mediated nitrosylation of ferrous MP11 (MP11-Fe(II)) is reported. Data were obtained between pH6.4 and 8.2, at 20.0°C. The NO2(-)-mediated conversion of MP11-Fe(II) to MP11-Fe(II)-NO requires one proton; accordingly, values of the apparent second-order rate constant (kon) decrease by about two orders of magnitude from (2.9±0.3)×10(1)M(-1)s(-1) to (5.0±0.6)×10(-1)M(-1)s(-1) upon increasing pH from 6.4 to pH8.2. The slope of the linear fitting of Logkon versus pH is -1.00±0.06. Values of kon for the NO2(-)-mediated nitrosylation of MP11-Fe(II) are similar to those of penta-coordinated cardiolipin-bound horse heart cyt c, exceeding by about two orders of magnitude those of wild-type horse heart cyt c. Present results highlight the role of heme distal residues in modulating horse heart cyt c reactivity.
Interdepartmental Laboratory for Electron Microscopy, Roma Tre University, I-00146 Roma, Italy; Institute of Protein Biochemistry, National Research Council, I-80131, Napoli, Italy. Electronic address: ascenzi@uniroma3.it.
Paolo
P
Ascenzi
Department of Clinical Sciences and Translational Medicine, University of Roma "Tor Vergata", I-00133 Roma, Italy; Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems, I-70126 Bari, Italy.
Diego
D
Sbardella
Department of Sciences, Roma Tre University, I-00146 Roma, Italy.
Marco
M
Fiocchetti
Department of Clinical Sciences and Translational Medicine, University of Roma "Tor Vergata", I-00133 Roma, Italy.
Roberto
R
Santucci
Department of Clinical Sciences and Translational Medicine, University of Roma "Tor Vergata", I-00133 Roma, Italy; Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems, I-70126 Bari, Italy.
Massimo
M
Coletta
D000818:Animals; D004227:Dithionite / Q000737:chemistry; D006418:Heme / Q000737:chemistry; D006736:Horses; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D009569:Nitric Oxide / Q000737:chemistry*; D009573:Nitrites / Q000737:chemistry*; D010544:Peroxidases / Q000737:chemistry*
D009573:Nitrites; D004227:Dithionite; D009569:Nitric Oxide; D006418:Heme; D007501:Iron; D010544:Peroxidases; C021799:microperoxidase
Ferrous microperoxidase-11; Kinetics; NO(2)(−)-mediated nitrosylation