19F nuclear magnetic resonance investigation of stereoselective binding of isoflurane to bovine serum albumin.
19F nuclear magnetic resonance investigation of stereoselective binding of isoflurane to bovine serum albumin.
复制标题
异氟烷与牛血清白蛋白立体选择性结合的 19F 核磁共振研究。
DOI：
10.1016/s0006-3495(96)79599-1
复制
发表时间：
1996
影响因子：
3.4
通讯作者：
Zhang,TT
中科院分区：
文献类型：
--
作者：
Xu,Y;Tang,P;Firestone,L;Zhang,TT
蛋白质或脂质是否是全身麻醉作用的主要靶点引起了相当大的争论。最近的体内研究表明，异氟烷的S（+）和R（-）对映体不是等效的，这意味着蛋白质的参与。牛血清白蛋白（BSA）是一种不含脂质的可溶性蛋白质，含有异氟烷和其他麻醉剂的特异性结合位点。因此，我们进行了19 F核磁共振测量，以确定异氟烷与BSA的结合是否具有立体选择性。测量异氟烷化学位移作为BSA浓度的函数，以确定游离和结合异氟烷之间的化学位移差异。通过测量19 F横向弛豫时间（T2）作为异氟烷浓度的函数来确定KD。通过评估游离和结合状态之间异氟烷交换导致的1/T2增加来确定结合持续时间。S（+）和R（-）对映异构体在化学位移和KD值方面没有表现出立体选择性（S（+）、R（-）和外消旋混合物的KD = 1.3 +/- 0.2 mM，平均值+/- SE）。尽管如此，在动态结合参数中观察到立体选择性; S（+）对映体结合的缔合和解离速率低于R（-）。
Whether proteins or lipids are the primary target sites for general anesthetic action has engendered considerable debate. Recent in vivo studies have shown that the S(+) and R(-) enantiomers of isoflurane are not equipotent, implying involvement of proteins. Bovine serum albumin (BSA), a soluble protein devoid of lipid, contains specific binding sites for isoflurane and other anesthetics. We therefore conducted 19F nuclear magnetic resonance measurements to determine whether binding of isoflurane to BSA was stereoselective. Isoflurane chemical shifts were measured as a function of BSA concentration to determine the chemical shift differences between the free and bound isoflurane. KD was determined by measuring the 19F transverse relaxation times (T2) as a function of isoflurane concentration. The binding duration was determined by assessing increases in 1/T2 as a result of isoflurane exchanging between the free and bound states. The S(+) and R(-) enantiomers exhibited no stereoselectivity in chemical shifts and KD values (KD = 1.3 +/- 0.2 mM, mean +/- SE, for S(+), R(-), and the racemic mixture). Nonetheless, stereoselectivity was observed in dynamic binding parameters; the S(+) enantiomer bound with slower association and dissociation rates than the R(-).