Abacavir modulates peroxynitrite-mediated oxidation of ferrous nitrosylated human serum heme-albumin

Paolo Ascenzi, Mauro Fasano

Research output: Contribution to journalArticlepeer-review


Human serum albumin (SA) is best known for its extraordinary ligand-binding capacity. Here, kinetics of peroxynitrite-mediated oxidation of SA-heme(II)-NO is reported. Peroxynitrite reacts with SA-heme(II)-NO leading to SA-heme(III) and {radical dot}NO by way of the transient SA-heme(III)-NO species. Abacavir facilitates peroxynitrite-mediated oxidation of SA-heme(II)-NO, in the absence and presence of CO2. Values of the second order rate constant for peroxynitrite-mediated oxidation of SA-heme(II)-NO are (6.5 ± 0.9) × 103 M-1 s-1 in the absence of CO2 and abacavir, (1.3 ± 0.2) × 105 M-1 s-1 in the presence of CO2, (2.2 ± 0.2) × 104 M-1 s-1 in the presence of abacavir, and (3.6 ± 0.3) × 105 M-1 s-1 in the presence of both CO2 and abacavir. The value of the first-order rate constant for {radical dot}NO dissociation from the SA-heme(III)-NO complex (=(1.8 ± 0.3) × 10-1 s-1) is CO2- and abacavir-independent, representing the rate-limiting step. Present data represent the first evidence for the allosteric modulation of SA-heme reactivity by heterotropic interaction(s).

Original languageEnglish
Pages (from-to)469-474
Number of pages6
JournalBiochemical and Biophysical Research Communications
Issue number2
Publication statusPublished - Feb 9 2007


  • Abacavir
  • Ferrous nitrosylated human serum heme-albumin
  • Human serum albumin
  • Kinetics
  • Peroxynitrite-mediated oxidation

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology


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