title: Time-resolved fluorescence of intestinal and liver fatty acid binding proteins: role of fatty acyl CoA and fatty acid.
abstract: The effect of fatty acyl CoA and fatty acid on the solution structure and dynamics of two intestinal enterocyte fatty acid binding proteins, intestinal (I-FABP) and liver (L-FABP), was examined by time-resolved fluorescence of FABP aromatic amino acid residues. I-FABP Trp displayed two rotational correlation times, 6.6 and 0.4 ns. reflecting motion of the protein as a whole and segmental mobility of Trp. Neither oleoyl CoA, oleic acid, nor CoASH altered overall I-FABP rotational correlation time. However, oleic acid and CoASH increased I-FABP Trp segmental mobility, while oleoyl CoA and CoASH decreased I-FABP Trp limiting anisotropy (order). The angle of I-FABP Trp "wobbling in a cone" was increased by ligands in the order oleoyl CoA > CoASH > oleic acid. L-FABP Trp segmental mobility. L-FABP overall rotational motion, in contrast to that of I-FABP, was significantly increased by ligands in the order oleoyl CoA > oleic acid > CoASH. cis-Parinaric acid and cis-parinaroyl CoA bound to L-FABP also reflected overall L-FABP motion but yielded longer rotational correlation times, 8.2 and 10.7 ns, than the respective apo-FABPs. Such effects were not observed with I-FABP. Finally, both cis-parinaric acid and cis-parinaroyl CoA were much less ordered in the I-FABP ligand binding site than with L-FABP. These observations suggest that the rotational dynamics of L-FABP and its conformation are more sensitive to ligands than I-FABP. Further, ligands such as fatty acids, fatty acyl CoAs, and/or CoASH differentially modulate the I-FABP and L-FABP dynamics, and the ligand binding sites of these proteins differ in their ability to order the ligands.
authors.affiliation: Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station 77843-4466, USA.
authors.forename: A
authors.initials: A
authors.lastname: Frolov
authors.forename: F
authors.initials: F
authors.lastname: Schroeder
mesh_terms: D000214:Acyl Coenzyme A / Q000737:chemistry* / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids / Q000737:chemistry* / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D018996:Myelin P2 Protein / Q000737:chemistry* / Q000378:metabolism; D009363:Neoplasm Proteins; D019308:Palmitic Acid / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: D000214:Acyl Coenzyme A; D002352:Carrier Proteins; C493320:Fabp1 protein, mouse; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D005456:Fluorescent Dyes; D018996:Myelin P2 Protein; D009363:Neoplasm Proteins; D019308:Palmitic Acid; C013641:parinaric acid