NO2 --mediated nitrosylation of ferrous microperoxidase-11

Paolo Ascenzi, Diego Sbardella, Marco Fiocchetti, Roberto Santucci, Massimo Coletta

Research output: Contribution to journalArticlepeer-review


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 pH 6.4 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) × 101 M- 1 s- 1 to (5.0 ± 0.6) × 10- 1 M- 1 s- 1 upon increasing pH from 6.4 to pH 8.2. 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.

Original languageEnglish
Pages (from-to)121-127
Number of pages7
JournalJournal of Inorganic Biochemistry
Publication statusPublished - Dec 1 2015


  • Ferrous microperoxidase-11
  • Kinetics
  • NO -mediated nitrosylation

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry


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