Thompson J, Winter N, Terwey D, Bratt J, Banaszak L
Department of Biochemistry, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
J Biol Chem. 1997 Mar 14;272(11):7140-50. doi: 10.1074/jbc.272.11.7140.
The crystal structure of the recombinant form of rat liver fatty acid-binding protein was completed to 2.3 A and refined to an R factor of 19.0%. The structural solution was obtained by molecular replacement using superimposed polyalanine coordinates of six intracellular lipid-binding proteins as a search probe. The entire amino acid sequence of rat liver fatty acid-binding protein along with an amino-terminal formyl-methionine was modeled in the crystal structure. In addition, the crystal was obtained in the presence of oleic acid, and the initial electron density clearly showed two fatty acid molecules bound within a central cavity. The carboxylate of one fatty acid molecule interacts with arginine 122 and is shielded from free solvent. It has an overall bent conformation. The more solvent-exposed carboxylate of the other oleate is located near the helix-turn-helix that caps one end of the beta-barrel, while the acyl chain lies in the interior. The cavity contains both polar and nonpolar residues but also shows extensive hydrophobic character around the nonpolar atoms of the ligands. The primary and secondary oleate binding sites appear to be totally interdependent, mainly because favorable hydrophobic interactions form between both aliphatic chains.
大鼠肝脏脂肪酸结合蛋白重组形式的晶体结构解析至2.3埃，并精修至R因子为19.0%。通过分子置换法获得结构解析结果，使用六个细胞内脂质结合蛋白的叠加聚丙氨酸坐标作为搜索探针。大鼠肝脏脂肪酸结合蛋白的完整氨基酸序列以及氨基末端的甲酰甲硫氨酸在晶体结构中得以建模。此外，晶体是在油酸存在的情况下获得的，初始电子密度清楚地显示出两个脂肪酸分子结合在中央腔内。一个脂肪酸分子的羧酸盐与精氨酸122相互作用，并被与游离溶剂隔离。它具有整体弯曲的构象。另一个油酸酯的羧酸盐更易暴露于溶剂中，位于覆盖β桶一端的螺旋-转角-螺旋附近，而酰基链位于内部。该腔包含极性和非极性残基，但在配体的非极性原子周围也表现出广泛的疏水特性。主要和次要的油酸酯结合位点似乎完全相互依赖，主要是因为两条脂肪链之间形成了有利的疏水相互作用。
