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Ibuprofen binding to secondary sites allosterically modulates the spectroscopic and catalytic properties of human serum heme–albumin
Author(s) -
di Masi Alessandra,
Gullotta Francesca,
Bolli Alessandro,
Fanali Gabriella,
Fasano Mauro,
Ascenzi Paolo
Publication year - 2011
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2010.07986.x
Subject(s) - heme , allosteric regulation , chemistry , human serum albumin , ibuprofen , ligand (biochemistry) , plasma protein binding , biochemistry , stereochemistry , binding site , enzyme , pharmacology , receptor , biology
The ibuprofen primary binding site FA3–FA4 is located in domain III of human serum albumin (HSA), the secondary clefts FA2 and FA6 being sited in domains I and II. Here, the thermodynamics of ibuprofen binding to recombinant Asp1–Glu382 truncated HSA (tHSA)–heme‐Fe(III) and nitrosylated tHSA–heme‐Fe(II), encompassing domains I and II only, is reported. Moreover, the allosteric effect of ibuprofen on the kinetics of tHSA–heme‐Fe(III)‐mediated peroxynitrite isomerization and nitrosylated tHSA–heme‐Fe(II) denitrosylation has been investigated. The present data indicate, for the first time, that the allosteric modulation of tHSA–heme and HSA–heme reactivity by ibuprofen depends mainly on drug binding to the FA2 and FA6 secondary sites rather than drug association with the FA3–FA4 primary cleft. Thus, tHSA is a valuable model with which to investigate the allosteric linkage between the heme cleft FA1 and the ligand‐binding pockets FA2 and FA6, all located in domains I and II of (t)HSA.