Conformational and binding properties of chicken liver basic fatty acid binding protein in solution

Abstract

The conformation of basic fatty acid binding protein from chicken liver and the binding properties of the apo protein toward 11-dansylamino-undecanoic acid were investigated by CD and fluorescence spectroscopy. In one set of experiments the binding process was followed by the appearance of induced optical activity in the absorption region of the dansyl chromophore. In a second set of experiments the binding process was followed by the large enhancement of emission fluorescence of the dansyl fluorophore. From the saturation curves, the stoichiometry of the complex and the binding constant of the fatty acid to the protein were precisely determined. The values of the dissociation constant determined with the two methods were in excellent agreement: we obtained KD = (1.0 +/- 0.1) x 10(-6) M in a 0.9: 1 stoichiometry. The native conformation of the protein is remarkably stable in a variety of solvent systems, including acetonitrile-water, ethylene glycol-water, and dioxane-water of various compositions. The CD results also showed that the binding of the fatty acid does not induce any appreciable change in the protein conformation. In a mixture of water and 2,2,2-trifluoroethanol 1:9 (v/v), the native conformation collapses and a new ordered structure is formed, characterized by a high amount of alpha-helix.

A Disulfide Bridge Allows for Site‐Selective Binding in Liver Bile Acid Binding Protein Thereby Stabilising the Orientation of Key Amino Acid Side Chains

“…BABPs are small molecular mass soluble proteins, found in the ileum and in the liver, displaying a large internal cavity able to host up to two bile salts. [1][2][3][4][5][6] They belong to the fatty acid binding protein family, the members of which behave as intracellular lipid chaperones capable of binding a wide variety of exogenous ligands [7] and play a role in the defence of the cell against different oxidative stresses. [8,9] A detailed mechanistic investigation of the binding mode of BABPs is of interest not only for clarifying their function but also for the design of ligands with properties (for instance, fluorescence) that may arise from selective occupancy of different protein sites.…”

Review: The liver bile acid‐binding proteins

“…9 From these experiments, the stoichiometry of binding was established in one ligand per protein molecule and the dissociation constant estimated to be of the order of 10…”

“…The primary structure was determined a few years later 8 while studies in solution explored the conformational and binding properties of the molecule. 9 In the meantime, another family of liver fatty acid-binding proteins was being characterized, a family that at one point began to be called the mammalian type liver FABPs. The first X-ray structure of a member of this group revealed that unlike other FABPs that had been shown to bind one fatty acid per protein molecule, rat liver FABP bound two molecules of oleic acid in its internal cavity.…”

Differential expression of L-FABP and L-BABP between fat and lean chickens

“…So far, L-BABP has never been found in mammalian species, but it has been identified and characterized in some vertebrates including fish, amphibians, reptiles, and birds (Ceciliani et al, 1994;Di Pietro et al, 1996Córdoba et al, 1999;Denovan-Wright et al, 2000;Ko et al, 2004;Jordal et al, 2006). Recent research on the structure of the L-BABP crystal showed that the capacity of L-BABP for binding to long-chain fatty acids is weak, but is strong for bile acid (Schievano et al, 1994;Beringhelli et al, 2001;Guariento et al, 2008), which is consistent with the presumption that the main function of L-BABP is to transport bile acids rather than fatty acids in chicken (Nichesola et al, 2004;Capaldi et al, 2006).…”