Liver fatty acid binding protein (FABP1) binds diverse endogenous lipids and is highly expressed in the human liver. Binding to FABP1 alters the metabolism and homeostasis of endogenous lipids in the liver. Drugs have also been shown to bind to rat FABP1, but limited data is available for human FABP1 (hFABP1). FABP1 has a large binding pocket and up to two fatty acids can bind to FABP1 simultaneously. We hypothesized that drug binding to hFABP1 results in formation of ternary complexes and that FABP1 binding alters drug metabolism. To test these hypotheses, native protein mass spectrometry (MS) and fluorescent 11-(dansylamino)undecanoic acid (DAUDA) displacement assays were used to characterize drug binding to hFABP1, and diclofenac oxidation by cytochrome P450 2C9 (CYP2C9) was studied in the presence and absence of hFABP1. DAUDA binding to hFABP1 involved high (K_d,1=0.2 µM) and low affinity (K_d,2 >10 µM) binding sites. Nine drugs bound to hFABP1 with K_d values ranging from 1 to 20 µM. None of the tested drugs completely displaced DAUDA from hFABP1 and fluorescence spectra showed evidence of ternary complex formation. Formation of DAUDA-hFABP1-diclofenac ternary complex was verified with native MS. Docking predicted diclofenac binding in the portal region of FABP1 with DAUDA in the binding cavity. The k_cat of diclofenac hydroxylation by CYP2C9 was decreased by ~50% (p<0.01) in the presence of FABP1. Together, these results suggest that drugs form ternary complexes with hFABP1 and that hFABP1 binding in the liver will alter drug metabolism and clearance.

中文翻译：

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药物与人肝脂肪酸结合蛋白 (FABP1) 形成三元复合物，FABP1 结合改变药物代谢

肝脏脂肪酸结合蛋白（FABP1）结合多种内源性脂质，并在人类肝脏中高度表达。与 FABP1 的结合会改变肝脏内源性脂质的代谢和稳态。药物也已被证明可以与大鼠 FABP1 结合，但有关人 FABP1 (hFABP1) 的可用数据有限。 FABP1 具有较大的结合袋，最多可以同时结合两个脂肪酸。我们假设药物与 hFABP1 结合导致三元复合物的形成，并且 FABP1 结合改变药物代谢。为了测试这些假设，使用天然蛋白质质谱 (MS) 和荧光 11-(丹磺氨基)十一烷酸 (DAUDA) 置换测定来表征药物与 hFABP1 的结合，并研究了细胞色素 P450 2C9 (CYP2C9) 存在下双氯芬酸的氧化作用。以及 hFABP1 的缺失。 DAUDA 与 hFABP1 的结合涉及高亲和力 (K _d,1 =0.2 µM) 和低亲和力 (K _d,2 >10 µM) 结合位点。九种药物与 hFABP1 结合，K _d值范围为 1 至 20 µM。所测试的药物均未完全取代 hFABP1 中的 DAUDA，并且荧光光谱显示三元复合物形成的证据。 DAUDA-hFABP1-双氯芬酸三元复合物的形成通过天然 MS 进行验证。对接预测双氯芬酸在 FABP1 的门户区域与结合腔中的 DAUDA 结合。在 FABP1 存在下，CYP2C9 对双氯芬酸羟基化的k _cat降低约 50% (p<0.01)。总之，这些结果表明药物与 hFABP1 形成三元复合物，并且 hFABP1 在肝脏中的结合将改变药物代谢和清除。