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 language | English |
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Pages (from-to) | 83-86 |
Number of pages | 4 |
Journal | Biochemical and Biophysical Research Communications |
Volume | 387 |
Issue number | 1 |
DOIs | |
Publication status | Published - 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