O2-mediated oxidation of ferrous nitrosylated human serum heme-albumin is limited by nitrogen monoxide dissociation

Paolo Ascenzi, Francesca Gullotta, Magda Gioia, Massimo Coletta, Mauro Fasano

Research output: Contribution to journalArticlepeer-review

Abstract

Human serum heme-albumin (HSA-heme-Fe) displays globin-like properties. Here, kinetics of O2-mediated oxidation of ferrous nitrosylated HSA-heme-Fe (HSA-heme-Fe(II)-NO) is reported. Values of the first-order rate constants for O2-mediated oxidation of HSA-heme-Fe(II)-NO (i.e., for ferric HSA-heme-Fe formation) and for NO dissociation from HSA-heme-Fe(II)-NO (i.e., for NO replacement by CO) are k=9.8×10-5 and 8.3×10-4s-1, and h=1.3×10-4 and 8.5×10-4s-1, in the absence and presence of rifampicin, respectively, at pH=7.0 and T=20.0°C. The coincidence of values of k and h indicates that NO dissociation represents the rate limiting step of O2-mediated oxidation of HSA-heme-Fe(II)-NO. Mixing HSA-heme-Fe(II)-NO with O2 does not lead to the formation of the transient adduct(s), but leads to the final ferric HSA-heme-Fe derivative. These results reflect the fast O2-mediated oxidation of ferrous HSA-heme-Fe and highlight the role of drugs in modulating allosterically the heme-Fe-atom reactivity.

Original languageEnglish
Pages (from-to)112-116
Number of pages5
JournalBiochemical and Biophysical Research Communications
Volume406
Issue number1
DOIs
Publication statusPublished - Mar 4 2011

Keywords

  • Allostery
  • Dioxygen-mediated oxidation
  • Ferrous nitrosylated human serum heme-albumin
  • Human serum albumin
  • Kinetics
  • Rifampicin

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology
  • Molecular Biology

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