Fatty-acid-binding protein facilitates the diffusion of oleate in a model cytosol system.
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.
Stewart
J M
JM
Department of Chemistry, Mount Allison University, New Brunswick, Canada.
Driedzic
W R
WR
Berkelaar
J A
JA
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
D002021:Buffers; D002352:Carrier Proteins; D050556:Fatty Acid-Binding Proteins; D009363:Neoplasm Proteins; D009829:Oleic Acids; D019301:Oleic Acid