Binding of disopyramide, methadone, dipyridamole, chlorpromazine, lignocaine and progesterone to the two main genetic variants of human alpha(1)-acid glycoprotein: Evidence for drug-binding difference between the variants and for the presence of two separate drug-binding sites on the alpha(1)-acid glycoprotein
Binding of disopyramide, methadone, dipyridamole, chlorpromazine, lignocaine and progesterone to the two main genetic variants of human alpha(1)-acid glycoprotein: Evidence for drug-binding difference between the variants and for the presence of two separate drug-binding sites on the alpha(1)-acid glycoprotein
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DOI：
10.1097/00008571-199610000-00004
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发表时间：
1996-10-01
期刊：
影响因子：
--
通讯作者：
Tillement, JP
中科院分区：
文献类型：
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作者：
Herve, F;Duche, JC;Tillement, JP
人α - 1-酸性糖蛋白（AAG）是一种血浆药物转运蛋白，主要有三种遗传变异，即a型变异和F1、S型变异，由两种不同的基因编码。用平衡透析法研究了从F1、S和A几乎相等比例的天然商业AAG中分离出的两种AAG基因产物（A变体和F1和S变体的混合物（60% F1和40% S））与二吡嗪、美沙酮、双吡达莫、氯丙嗪、利多卡因和黄体酮的结合。结果发现，双吡喃和美沙酮选择性结合A变异体，双嘧达莫优先结合F1S变异体。利多卡因和氯丙嗪对AAG的F1S变异有轻微的偏好。A变体和F1S混合物之间的药物结合差异证实了先前的研究，其中发现丙咪嗪与A变体选择性结合，华法林和米非司酮与F1S混合物选择性结合。这些结果表明，根据其单独的遗传来源，每种AAG变体具有特定的药物转运作用。与（未分离的）商业AAG和一系列测试配体进行的对照结合实验的结果与单独的AAG变体的结果一致，在商业蛋白中A变体的比例（27%）和F1变体的比例（73%）。此外，在平衡透析置换实验中，使用了双吡嗪、美沙酮、双嘧达莫、氯丙嗪、利多卡因和黄体酮，研究了A变体用丙咪嗪标记的结合位点和F1S变体混合物用华法林标记的结合位点之间的相互作用。发现后四种配体竞争性地抑制华法林与F1S变体混合物的结合，而它们都抑制丙咪嗪与A变体的结合。从这种抑制实验中获得的每个AAG变体的配体结合常数与直接结合研究中确定的配体结合常数相当。由于A变异体和F1S变异体与其特定配体的相互作用的随机测量值分别约为1(1)，因此可以得出结论，这些配体通过一个共同的结合位点与这些变异体结合。这些结果表明，AAG分子的配体至少有两个独立的结合位点，表现出不同的特异性和定位，而不是一般认为的一个位点。讨论了与单独的AAG变体结合结果的可能的药理学和临床后果。
Human alpha 1-acid glycoprotein (AAG), a plasma drug transport protein, has three main genetic variants, the A variant and the F1 and S variants, which are encoded by two different genes. The binding of disopyramide, methadone, dipryidamole, chlorpromazine, lignocaine and progesterone to the two gene products of AAG-the A variant and a mixture of the F1 and S variants (60% F1 and 40% S)-separated by chromatography from native commercial AAG, a mixture of almost equal proportions of the F1, S and A variants, was studied by equilibrium dialysis. A selective binding of disopyramide and methadone to the A variant and a preferential binding of dipyridamole to the F1S variant mixture were found. Lignocaine and chlorpromazine had a slight preference to the F1S variants of AAG. The differences in drug-binding demonstrated between the A variant and the F1S mixture confirmed those of a previous study, in which a selective binding of imipramine to the A variant and of warfarin and mifepristone to the F1S mixture have been found. These results indicate specific drug transport roles for each AAG variant, according to its separate genetic origin. The results of control binding experiments performed with (unfractionated) commercial AAG and the series of tested ligands concurred with that for the separate AAG variants, with respect to the proportion of the A variant (27%) and that of the F1 and variants (73%) in the commercial protein. In addition, disopyramide, methadone, dipyridamole, chlorpromazine, lignocaine and progesterone were used in equilibrium dialysis displacement experiments to study interactions on binding sites labelled with imipramine for the A variant and with warfarin for the F1S variant mixture. The four later ligands were found to competitively inhibit the binding of warfarin to the F1S variant mixture and all of them that of imipramine to the A variant. The ligands association constants to each AAG variant obtained from such inhibitory experiments were comparable to those determined in the direct binding studies. As the stochiometry of the interactions of the A variant and the F1S variants, respectively, with their specific ligands was approximately one (1), it was concluded that these ligands bind to each of these variants via a single common binding site. These results indicate that the AAG molecule would have for its ligands at least two separate binding sites, showing different specificity and localization, and not one site, as it is generally assumed. The possible pharmacological and clinical consequences of the binding results with the separate AAG variants are discussed.