James E L, Bottomley S P
Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, 3168, Australia.
Arch Biochem Biophys. 1998 Aug 15;356(2):296-300. doi: 10.1006/abbi.1998.0751.
The polymerization of alpha1-antitrypsin within the hepatic cell leads to alpha1-antitrypsin deficiency. Both the conformational changes and the kinetics of the polymerization process are poorly understood. Here we describe fluorescence experiments investigating the polymerization reaction using the fluorescent probe4, 4'-dianilino-1,1'-binaphthyl-5,5'-disulfonate (bis-ANS) which bound to both native and polymerized alpha1-antitrypsin. Biphasic changes in bis-ANS fluorescence were observed during formation of alpha1-antitrypsin polymers. Initially a rapid increase in fluorescence signal was observed; it was followed by a gradual reduction in fluorescence signal. The first phase is a conformational change in which the A beta-sheet of alpha1-antitrypsin opens, whereas the second phase represents the insertion of the reactive center loop into the A beta-sheet of another molecule and therefore determines the rate of the polymerization process.
α1-抗胰蛋白酶在肝细胞内的聚合导致α1-抗胰蛋白酶缺乏症。聚合过程的构象变化和动力学都了解甚少。在此，我们描述了荧光实验，该实验使用与天然和聚合的α1-抗胰蛋白酶都结合的荧光探针4,4'-二苯胺基-1,1'-联萘-5,5'-二磺酸盐（双-ANS）来研究聚合反应。在α1-抗胰蛋白酶聚合物形成过程中观察到双-ANS荧光的双相变化。最初观察到荧光信号迅速增加；随后荧光信号逐渐降低。第一阶段是α1-抗胰蛋白酶的Aβ-折叠打开的构象变化，而第二阶段代表反应中心环插入另一个分子的Aβ-折叠中，因此决定了聚合过程的速率。
