title: Ibuprofen binding to secondary sites allosterically modulates the spectroscopic and catalytic properties of human serum heme-albumin.
abstract: 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.
authors.affiliation: Department of Biology, and Interdepartmental Laboratory of Electron Microscopy, University Roma Tre, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: di Masi
authors.forename: Francesca
authors.initials: F
authors.lastname: Gullotta
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bolli
authors.forename: Gabriella
authors.initials: G
authors.lastname: Fanali
authors.forename: Mauro
authors.initials: M
authors.lastname: Fasano
authors.forename: Paolo
authors.initials: P
authors.lastname: Ascenzi
mesh_terms: D000495:Allosteric Site; D055162:Biocatalysis; D006418:Heme / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007052:Ibuprofen / Q000737:chemistry* / Q000378:metabolism; D007536:Isomerism; D008958:Models, Molecular; D030421:Peroxynitrous Acid / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012709:Serum Albumin / Q000737:chemistry* / Q000378:metabolism; D013053:Spectrophotometry
chemical_list: D012709:Serum Albumin; D030421:Peroxynitrous Acid; D006418:Heme; D007052:Ibuprofen