title: Determination of the binding properties of the uremic toxin phenylacetic acid to human serum albumin.
abstract: Uremic toxins are compounds normally excreted in urine that accumulate in patients with chronic kidney disease as a result of decreased renal clearance. Phenylacetic acid (PAA) has been identified as a new protein bound uremic toxin. The purpose of this study was to investigate in vitro the interaction between PAA and human serum albumin (HSA) at physiological and pathological concentrations. We used ultrafiltration to show that there is a single high-affinity binding site for PAA on HSA, with a binding constant on the order of 3.4 × 10(4) M(-1) and a maximal stoichiometry of 1.61 mol per mole. The PAA, at the concentration reported in end-stage renal patients, was 26% bound to albumin. Fluorescent probe competition experiments demonstrated that PAA did not bind to Sudlow's site I (in subdomain IIA) and only weakly bind to Sudlow's site II (in subdomain IIIA). The PAA showed no competition with other protein-bound uremic toxins such as p-cresyl-sulfate or indoxyl sulfate for binding to serum albumin. Our results provide evidence that human serum albumin can act as carrier protein for phenylacetic acid.
authors.affiliation: Medical Sciences Graduate Program, Federal University Fluminense, Niteroi, Rio de Janeiro, Brazil.
authors.forename: Juliana F
authors.initials: JF
authors.lastname: Saldanha
authors.affiliation: Univ Lyon, INSA-Lyon, UMR 1060 INSERM, CarMeN, F-69621 Villeurbanne, France.
authors.forename: Dan
authors.initials: D
authors.lastname: Yi
authors.affiliation: Cardiovascular Sciences Graduate Program, Federal University Fluminense, Niteroi, Rio de Janeiro, Brazil.
authors.forename: Milena B
authors.initials: MB
authors.lastname: Stockler-Pinto
authors.affiliation: Univ Lyon, INSA-Lyon, UMR 1060 INSERM, CarMeN, F-69621 Villeurbanne, France.
authors.forename: Hédi A
authors.initials: HA
authors.lastname: Soula
authors.affiliation: Univ Lyon, INSA-Lyon, UMR 5246 CNRS, ICBMS, F-69621 Villeurbanne, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Chambert
authors.affiliation: Univ Lyon, INSA-Lyon, UMR 1060 INSERM, CarMeN, F-69621 Villeurbanne, France; Department of Nephrology, Centre Hospitalier Lyon Sud, Pierre Bénite, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Fouque
authors.affiliation: Medical Sciences Graduate Program, Federal University Fluminense, Niteroi, Rio de Janeiro, Brazil; Cardiovascular Sciences Graduate Program, Federal University Fluminense, Niteroi, Rio de Janeiro, Brazil.
authors.forename: Denise
authors.initials: D
authors.lastname: Mafra
authors.affiliation: Univ Lyon, INSA-Lyon, UMR 1060 INSERM, CarMeN, F-69621 Villeurbanne, France. Electronic address: christophe.soulage@insa-lyon.fr.
authors.forename: Christophe O
authors.initials: CO
authors.lastname: Soulage
mesh_terms: D002460:Cell Line; D006801:Humans; D010648:Phenylacetates / Q000737:chemistry*; D011485:Protein Binding; D000072417:Protein Domains; D051436:Renal Insufficiency, Chronic / Q000097:blood; D012709:Serum Albumin / Q000737:chemistry* / Q000378:metabolism
chemical_list: D010648:Phenylacetates; D012709:Serum Albumin; C025136:phenylacetic acid
keywords: Chronic kidney disease; Human serum albumin; Phenylacetic acid; Protein binding; Uremic syndrome; Uremic toxin