High Relaxivity Supramolecular Adducts Between Human-Liver Fatty-Acid-Binding Protein and Amphiphilic GdIII Complexes: Structural Basis for the Design of Intracellular Targeting MRI Probes
High Relaxivity Supramolecular Adducts Between Human-Liver Fatty-Acid-Binding Protein and Amphiphilic GdIII Complexes: Structural Basis for the Design of Intracellular Targeting MRI Probes
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DOI：
10.1002/chem.201103778
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发表时间：
2012-08-01
影响因子：
4.3
通讯作者：
Assfalg, Michael
中科院分区：
文献类型：
--
作者：
D'Onofrio, Mariapina;Gianolio, Eliana;Assfalg, Michael
已知与非极性片段连接的钆络合物被有效地内化到各种细胞类型中，包括肝细胞。两种脂质功能化的钆螯合物已被研究用于靶向人肝脂肪酸结合蛋白（hL-FABP）作为增加细胞内定向MRI探针的灵敏度和特异性的手段。hL-FABP是肝细胞中最丰富的胞质脂质结合蛋白，显示出与参与脂质信号传导的多种配体相互作用的能力，并且被认为是护送药物穿过细胞的专性载体。的脂肪酸和胆汁酸基钆配合物与hL-FABP的相互作用模式已被其特征在于在溶液中的弛豫和NMR实验与接近生理蛋白浓度。我们已经介绍了顺磁诱导的蛋白质NMR信号强度变化的分析作为定量工具，用于确定结合化学计量和精确的金属离子中心定位在proteinligand超分子加合物。然后，通过使用快速数据驱动的对接方法，一些额外的NMR衍生的限制足以将配体分子定位在蛋白质结合位点中。与油酸和钆配合物的弛豫和13 C NMR竞争实验揭示了异型加合物的形成，这表明两亲性化合物可能与生理配体共存于蛋白质腔中。基于脂肪酸和胆汁酸的复合物之间的加合物形成的差异为细胞内靶向探针的改进的分子设计提供了基础。
Gadolinium complexes linked to an apolar fragment are known to be efficiently internalized into various cell types, including hepatocytes. Two lipid-functionalized gadolinium chelates have been investigated for the targeting of the human liver fatty acid binding protein (hL-FABP) as a means of increasing the sensitivity and specificity of intracellular-directed MRI probes. hL-FABP, the most abundant cytosolic lipid binding protein in hepatocytes, displays the ability to interact with multiple ligands involved in lipid signaling and is believed to be an obligate carrier to escort lipidic drugs across the cell. The interaction modes of a fatty acid and a bile acid based gadolinium complex with hL-FABP have been characterized by relaxometric and NMR experiments in solution with close-to-physiological protein concentrations. We have introduced the analysis of paramagnetic-induced protein NMR signal intensity changes as a quantitative tool for the determination of binding stoichiometry and of precise metal-ion-center positioning in proteinligand supramolecular adducts. A few additional NMR-derived restraints were then sufficient to locate the ligand molecules in the protein binding sites by using a rapid data-driven docking method. Relaxometric and 13C NMR competition experiments with oleate and the gadolinium complexes revealed the formation of heterotypic adducts, which indicates that the amphiphilic compounds may co-exist in the protein cavity with physiological ligands. The differences in adduct formation between fatty acid and bile acid based complexes provide the basis for an improved molecular design of intracellular targeted probes.