title: Mass spectrometry and NMR analysis of ligand binding by human liver fatty acid binding protein.
abstract: Human liver fatty acid binding protein (hL-FABP) is the most abundant cytosolic protein in the liver. This protein plays important roles associated to partitioning of fatty acids (FAs) to specific metabolic pathways, nuclear signaling and protection against oxidative damage. The protein displays promiscuous binding properties and can bind two internal ligands, unlike FABPs from other tissues. Different topologies for the ligand located in the more accessible site have been reported, with either a 'head-in' or 'head-out' orientation of the carboxylate end. Electrospray-ionization mass spectrometry and nuclear magnetic resonance titrations are employed here in order to investigate in further detail the binding properties of this system, the equilibria established in solution and the pH dependence of the complexes. The results are consistent with two binding sites with different affinity and a unique head-out topology for the second molecule of either ligand. Competition experiments indicate a higher affinity for oleic acid relative to palmitic acid at each binding site.
authors.affiliation: Department of Biotechnology and Biosciences, Piazza della Scienza 2, University of Milano-Bicocca, 20126, Milan, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Santambrogio
authors.forename: F
authors.initials: F
authors.lastname: Favretto
authors.forename: M
authors.initials: M
authors.lastname: D'Onofrio
authors.forename: M
authors.initials: M
authors.lastname: Assfalg
authors.forename: R
authors.initials: R
authors.lastname: Grandori
authors.forename: H
authors.initials: H
authors.lastname: Molinari
mesh_terms: D050556:Fatty Acid-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D019301:Oleic Acid / Q000737:chemistry / Q000378:metabolism; D019308:Palmitic Acid / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D050556:Fatty Acid-Binding Proteins; D008024:Ligands; D011994:Recombinant Proteins; D019301:Oleic Acid; D019308:Palmitic Acid
keywords: electrospray-ionization mass spectrometry; nuclear magnetic resonance; oleic acid; palmitic acid; protein-ligand interactions