title: Fatty-acid-binding protein facilitates the diffusion of oleate in a model cytosol system.
abstract: The proposed function of fatty-acid-binding proteins in facilitating the diffusion of their ligand has been examined in a cytosolic model using a steady-state diaphragm cell apparatus. The white muscle of ocean pout (Macrozoarces americanus) does not have a fatty-acid-binding protein: nor does it exhibit detectable beta-oxidative capacity, and as such is a good source of cytosol preparation. After determining the diffusion coefficient of oleate in this medium, fatty-acid-binding protein, isolated from the ventricle of this animal, was added and the apparent diffusion coefficient was again determined. The presence of the fatty-acid-binding protein increased the apparent diffusion coefficient of this long-chain fatty acid about 6-fold, from 0.087 x 10(-5) cm2.s-1 to 0.58 x 10(-5)cm2.s-1. This confirms the facilitated diffusion hypothesis as one role of fatty-acid-binding protein. The diffusion coefficients of oleate in 50 mM-sodium phosphate buffer, pH 7.4, at 10 degrees C and 25 degrees C (0.15 x 10(-5) cm2.s-1 and 0.28 x 10(-5) cm2.s-1 respectively) were also measured.
authors.affiliation: Department of Chemistry, Mount Allison University, New Brunswick, Canada.
authors.forename: J M
authors.initials: JM
authors.lastname: Stewart
authors.forename: W R
authors.initials: WR
authors.lastname: Driedzic
authors.forename: J A
authors.initials: JA
authors.lastname: Berkelaar
mesh_terms: D000818:Animals; D002021:Buffers; D002352:Carrier Proteins / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D004058:Diffusion; D050556:Fatty Acid-Binding Proteins; D005399:Fishes; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological; D009132:Muscles / Q000648:ultrastructure; D009363:Neoplasm Proteins; D019301:Oleic Acid; D009829:Oleic Acids / Q000378:metabolism*; D014783:Viscosity
chemical_list: D002021:Buffers; D002352:Carrier Proteins; D050556:Fatty Acid-Binding Proteins; D009363:Neoplasm Proteins; D009829:Oleic Acids; D019301:Oleic Acid