1adl
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ADIPOCYTE LIPID BINDING PROTEIN COMPLEXED WITH ARACHIDONIC ACID: X-RAY CRYSTALLOGRAPHIC AND TITRATION CALORIMETRY STUDIES
OverviewOverview
The association of the adipocyte lipid-binding protein (ALBP) with, arachidonic acid (all cis, 20:4 delta 5,8,11,14) and oleic acid (cis, 18:1, delta 9) has been examined by titration calorimentry. In addition, the, crystal structure of ALBP with bound arachidonic acid has also been, obtained. Crystallographic analysis of the arachidonic acid.ALBP complex, along with the previously reported oleic acid-ALBP structure (Xu, Z., Bernlohr, D. A., and Banaszak, L. J. (1993) J. Biol. Chem. 268, 7874-7884), provides a framework for the molecular examination of protein-lipid, association. Isothermal titration calorimetry revealed high affinity, association of both unsaturated fatty acids with the protein. The, calorimetric data yielded the following thermodynamic parameters for, arachidonic acid: Kd = 4.4 microM, n = 0.8, delta G = -7370 cal/mol, delta, H = -6770 cal/mol, and T delta S = +600 cal/mol. For oleic acid, the, thermodynamic parameters were Kd = 2.4 microM, n = 0.9, delta G = -7770, cal/mol, delta H = -6050 cal/mol, and T delta S = +1720 cal/mol. The, identification of thermodynamically dominating enthalpic factors for both, fatty acids are consistent with the crystallographic studies demonstrating, the interaction of the fatty acid carboxylate with a combination of, Arg106, Arg126, and Tyr128. The crystallographic refinement of the, protein-arachidonate complex was carried out to 1.6 A with the resultant R, factor of 0.19. Within the cavity of the crystalline binding protein, the, arachidonate was found in a hairpin conformation. The conformation of the, bound ligand is consistent with acceptable torsional angles and the four, cis double bonds in arachidonate. These results demonstrate that, arachidonate is a ligand for ALBP. They provide thermodynamic and, structural data concerning the physical basis for protein-lipid, interaction and suggest that intracellular lipid-binding proteins may, mediate the biological effects of polyunsaturated fatty acids in vivo.
About this StructureAbout this Structure
1ADL is a Single protein structure of sequence from Mus musculus with O, ACD and PPI as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Adipocyte lipid-binding protein complexed with arachidonic acid. Titration calorimetry and X-ray crystallographic studies., LaLonde JM, Levenson MA, Roe JJ, Bernlohr DA, Banaszak LJ, J Biol Chem. 1994 Oct 14;269(41):25339-47. PMID:7929228
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