Ibuprofen modulates allosterically NO dissociation from ferrous nitrosylated human serum heme-albumin by binding to three sites

Paolo Ascenzi, Alessandra di Masi, Giampiero De Sanctis, Massimo Coletta, Mauro Fasano

Research output: Contribution to journalArticlepeer-review

Abstract

Human serum albumin (HSA) is a monomeric allosteric protein. Here, the effect of ibuprofen on denitrosylation kinetics (koff) and spectroscopic properties of HSA-heme-Fe(II)-NO is reported. The koff value increases from (1.4 ± 0.2) × 10-4 s-1, in the absence of the drug, to (9.5 ± 1.2) × 10-3 s-1, in the presence of 1.0 × 10-2 M ibuprofen, at pH 7.0 and 10.0 °C. From the dependence of koff on the drug concentration, values of the dissociation equilibrium constants for ibuprofen binding to HSA-heme-Fe(II)-NO (K1 = (3.1 ± 0.4) × 10-7 M, K2 = (1.7 ± 0.2) × 10-4 M, and K3 = (2.2 ± 0.2) × 10-3 M) were determined. The K3 value corresponds to the value of the dissociation equilibrium constant for ibuprofen binding to HSA-heme-Fe(II)-NO determined by monitoring drug-dependent absorbance spectroscopic changes (H = (2.6 ± 0.3) × 10-3 M). Present data indicate that ibuprofen binds to the FA3-FA4 cleft (Sudlow's site II), to the FA6 site, and possibly to the FA2 pocket, inducing the hexa-coordination of HSA-heme-Fe(II)-NO and triggering the heme-ligand dissociation kinetics.

Original languageEnglish
Pages (from-to)83-86
Number of pages4
JournalBiochemical and Biophysical Research Communications
Volume387
Issue number1
DOIs
Publication statusPublished - Sep 11 2009

Keywords

  • Allostery
  • Ferrous nitrosylated human serum heme-albumin
  • Ibuprofen-dependent absorbance spectroscopic properties
  • Ibuprofen-dependent denitrosylation
  • Kinetics
  • Thermodynamics

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology
  • Molecular Biology

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