Koloczek H, Guz A, Kaszycki P
University of Agriculture, Department of Biochemistry, Kraków, Poland.
J Protein Chem. 1996 Jul;15(5):447-54. doi: 10.1007/BF01886851.
The time dependence of the human alpha 1-antitrypsin polymerization process was studied by means of the intrinsic fluorescence stopped-flow technique as well as the fluorescence-quenching-resolved spectra (FQRS) method and native PAGE. The polymerization was induced by mild denaturing conditions (1 M GuHCl) and temperature. The data show that the dimer formation reaction under mild conditions was followed by an increase of fluorescence intensity. This phenomenon is highly temperature sensitive. The structure of alpha 1-antitrypsin dimer resembles the conformation of antithrombin III dimer. In the presence of the denaturant the polymerization process is mainly limited to the dimer state. The alpha 1-antitrypsin activity measurements confirm monomer-to-dimer transition under these conditions. These results are in contrast to the polymerization process induced by temperature, where the dimer state is an intermediate step leading to long-chain polymers. On the basis of stopped-flow and electrophoretic data it is suggested that both C-sheet as well as A-sheet mechanisms contribute to the polymerization process under mild conditions.
采用内源荧光停流技术、荧光猝灭分辨光谱（FQRS）法和非变性聚丙烯酰胺凝胶电泳（native PAGE）研究了人α1-抗胰蛋白酶聚合过程的时间依赖性。通过温和的变性条件（1 M盐酸胍）和温度诱导聚合反应。数据表明，在温和条件下二聚体形成反应之后荧光强度增加。这种现象对温度高度敏感。α1-抗胰蛋白酶二聚体的结构类似于抗凝血酶III二聚体的构象。在变性剂存在下，聚合过程主要局限于二聚体状态。α1-抗胰蛋白酶活性测量证实了在这些条件下单体向二聚体的转变。这些结果与温度诱导的聚合过程相反，在温度诱导的聚合过程中，二聚体状态是导致长链聚合物形成的中间步骤。基于停流和电泳数据，表明在温和条件下C片层以及A片层机制均对聚合过程有贡献。
