Binding of fluorescent 7-amino-4-nitrobenzoxadiazole derivatives to bovine serum albumin.
作者:YASUO MATUSHITA、MASAAKI TAKAHASHI、IKUO MORIGUCHI
DOI:10.1248/cpb.34.333
日期:——
The quantum yield and binding to bovine serum albumin (BSA) were investigated with various fluorescent 7-alkylamino (bearing 2-12 carbon atoms), 7-benzylamino, and 7-p-methoxybenzyl-amino derivatives of 4-nitrobenzoxadiazole (NBD). Among them, alkylamino derivatives gave high quantum yield in both ethanol and BSA solution, and greater affinity to BSA was found with those having a longer alkyl chain. In particular, those with C8-C12 alkyl chains may be useful in research on hydrophobic regions as fluorescent probes. In the binding of these probes to BSA, the logarithm of the primary association constant increased linearly with increase in the length of the side chain; a hydrophobic cleft similar to that on the human serum albumin molecule was suggested to exist also on the BSA molecule. In the investigation of the binding displacement of 7-amino-NBD derivatives based on Sudlow's classification, almost no displacement was observed with site II drugs, ibuprofen and flufenamic acid. However, diazepam (a site II drug) showed different behavior from other site II drugs. It was particularly interesting that the difference of the displacing behavior between diazepam and other site II drugs increases with increase of the side chain length of the alkylamino-NBD probes.
研究了量子产率和与牛血清白蛋白(BSA)的结合情况,采用了各种荧光的7-烷基氨基(含有2-12个碳原子)、7-苯基氨基和7-对甲氧基苯基氨基衍生物的4-硝基苯并噁二唑(NBD)。其中,烷基氨基衍生物在乙醇和BSA溶液中均表现出较高的量子产率,且具有较长烷基链的衍生物与BSA有更强的亲和力。特别是C8-C12烷基链的衍生物在研究疏水区域作为荧光探针时可能会很有用。在这些探针与BSA结合的过程中,主要结合常数的对数与侧链长度的增加呈线性关系;推测BSA分子上也存在类似于人血清白蛋白分子上的疏水裂缝。根据Sudlow分类法对7-氨基-NBD衍生物的结合置换进行研究时,几乎没有观察到与II位点药物如布洛芬和氟芬那酸的置换。然而,地西泮(一个II位点药物)的行为与其他II位点药物不同。特别有趣的是,地西泮与其他II位点药物之间的置换行为差异随着烷基氨基-NBD探针侧链长度的增加而增加。