Abstract：
The plasma protein α1-acid glycoprotein (AGP) primarily affects the pharmacokinetics of basic drugs. There are two AGP variants in humans, A and F1*S, exhibiting distinct drug-binding selectivity. Elucidation of the drug-binding selectivity of human AGP variants is essential for drug development and personalized drug therapy. Herein, we aimed to establish the contribution of amino acids 112 and 114 of human AGP to drug-binding selectively. Both amino acids are located in the drug-binding region and differ between the variants. Phe112/Ser114 of the A variant and its equivalent residues in the F1*S variant (Leu112/Phe114) were swapped with each other. Binding experiments were then conducted using the antiarrhythmic drug disopyramide, which selectively binds to the A variant. A significant decrease in the bound fraction was observed in each singly mutated A protein (Phe112Leu or Ser114Phe). Moreover, the bound fraction of the double A mutant (Phe112Leu/Ser114Phe) was decreased to that of wild-type F1*S. Intriguingly, the double F1*S mutant (Leu112Phe/Phe114Ser), in which residues were swapped with those of the A variant, showed only partial restoration in binding. The triple F1*S mutant (Leu112Phe/Phe114Ser/Asp115Tyr), where position 115 is thought to contribute to the difference in pocket size between variants, showed a further recovery in binding to 70% of that of wild-type A. These results were supported by thermodynamic analysis and acridine orange binding, which selectively binds the A variant. Together, these data indicate that, in addition to direct interaction with Phe112 and Ser114, the binding pocket size contributed by Tyr115 is important for the drug-binding selectivity of the A variant.
摘要：
血浆蛋白α1-酸性糖蛋白（AGP）主要影响基础药物的药代动力学。人类有两种AGP变体，A和F1*S，表现出不同的药物结合选择性。阐明人AGP变体的药物结合选择性对于药物开发和个性化药物治疗至关重要。在这里，我们旨在确定人AGP氨基酸112和114对药物选择性结合的贡献.两种氨基酸都位于药物结合区并且在变体之间不同。将A变体的Phe112/Ser114及其在F1*S变体中的等效残基(Leu112/Phe114)彼此交换。然后使用抗心律失常药物二吡胺进行结合实验，它选择性地与A变体结合。在每个单突变的A蛋白(Phe112Leu或Ser114Phe)中观察到结合分数的显著降低。此外，双A突变体(Phe112Leu/Ser114Phe)的结合分数降低至野生型F1*S。有趣的是，双F1*S突变体（Leu112Phe/Phe114Ser），其中残基与A变体的残基交换，在结合中仅显示部分恢复。三重F1*S突变体（Leu112Phe/Phe114Ser/Asp115Tyr），位置115被认为是导致变体之间口袋大小差异的原因，显示与野生型A结合的70％进一步恢复。这些结果得到了热力学分析和吖啶橙结合的支持，其选择性地结合A变体。一起,这些数据表明，除了与Phe112和Ser114直接相互作用外,Tyr115贡献的结合口袋大小对于A变体的药物结合选择性也是重要的。
