Albumin binding sites for etodolac enantiomers.
Albumin binding sites for etodolac enantiomers.
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DOI：
10.1002/(sici)1520-636x(1996)8:3
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发表时间：
1996
期刊：
影响因子：
2
通讯作者：
I. Mignot;N. Presle;F. Lapicque;C. Monot;R. Dropsy;P. Netter
中科院分区：
文献类型：
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作者：
I. Mignot;N. Presle;F. Lapicque;C. Monot;R. Dropsy;P. Netter
非甾体类抗炎药（NSAID）与人血清白蛋白（HSA）强烈结合，主要结合位点I和II。本研究的目的是使用平衡透析法表征依托度酸对映体在生理条件下（580 μ M HSA）的结合位点。依托度酸对映体，单独或以不同的比例，蛋白结合进行了研究，以评估它们之间的潜在竞争。我们的结果表明，（S）-依托度酸比（R）-依托度酸与HSA的结合更强。仅在高浓度竞争剂下观察到一种对映异构体被其对映体置换，并且对于（S）-型更为明显。通过白蛋白、丹磺酰胺和丹磺肌氨酸的位点I和II的特异性探针对映体进行置换研究，结果表明，（R）-依托度酸被这两种探针轻微置换，而（S）-依托度酸的游离浓度在丹磺肌氨酸存在下显著增加。此外，配体与位点I和II的结合通常受碱性pH、氯离子和脂肪酸的影响。对于依托度酸，0.1和1 M氯离子的存在和pH值的增加（5.5-9）降低了两种对映体的结合。加入辛酸得到相同的结果。相反地，向蛋白质溶液中加入油酸、棕榈酸或硬脂酸可增加（R）-依托度酸的结合，但降低其对映体的结合。所有这些发现表明（R）-和（S）-依托度酸主要与HSA的位点II相互作用，并且（R）-异构体在生理条件下也与位点I结合。
Non-steroidal anti-inflammatory drugs (NSAIDs) are strongly bound to human serum albumin (HSA), mainly to sites I and II. The aim of this study was to characterize the binding site(s) of etodolac enantiomers under physiological conditions (580 microM HSA) using equilibrium dialysis. The protein binding of etodolac enantiomers, alone or in various ratios, was studied in order to evaluate the potential competition between them. Our results showed that (S)-etodolac was more strongly bound to HSA than (R)-etodolac. The displacement of one enantiomer by its antipode was observed only at high concentrations of the competitor, and was more pronounced for (S)-form. Displacement studies of the enantiomers by specific probes of sites I and II of albumin, dansylamide, and dansylsarcosine, respectively, showed that (R)-etodolac was slightly displaced by both these probes whereas the free concentration of (S)-etodolac increased markedly in the presence of dansylsarcosine. Moreover, the binding of ligands to sites I and II is usually affected by alkaline pH, by chloride ions, and by fatty acids. For etodolac, the presence of 0.1 and 1 M chloride ions and increasing pH (5.5-9) decreased the binding of both enantiomers. The same result was obtained with addition of octanoic acid. Conversely, the addition of oleic, palmitic, or stearic acid to the protein solution increased the binding of (R)-etodolac, but decreased that of its antipode. All these findings suggest (R)- and (S)-etodolac interact mainly with site II of HSA, and that the (R)-isomer is also bound to site I under physiological conditions.