Darby N J, Creighton T E
European Molecular Biology Laboratory, Heidelberg, Germany.
Biochemistry. 1995 Sep 19;34(37):11725-35. doi: 10.1021/bi00037a009.
The two thioredoxin-like domains of human protein disulfide isomerase (PDI) have been produced in bacteria as individual soluble, folded protein molecules, and their functional properties have been compared to those of intact PDI. The two individual domains were very similar in their functional properties, and there were no indications of synergy between them, so it is unlikely that they have intrinsically different functions in PDI. Both domains efficiently introduced disulfide bonds into unfolded model proteins and peptides but were less efficient than PDI with folded substrate protein molecules. Relative to PDI, neither domain had substantial activity in catalyzing disulfide bond isomerization. This pattern of activities is very similar to that of the bacterial catalyst DsbA and probably reflects similarities in the catalytic mechanisms of these proteins. The differences in activity between PDI and its thioredoxin-like domains suggest that other features of the PDI molecule are also required for its complete range of thiol-disulfide exchange activities.
人蛋白二硫键异构酶（PDI）的两个硫氧还蛋白样结构域已在细菌中作为单独的可溶性折叠蛋白分子产生，并且已将它们的功能特性与完整PDI的功能特性进行了比较。这两个单独的结构域在功能特性上非常相似，并且没有它们之间协同作用的迹象，因此它们在PDI中不太可能具有本质上不同的功能。两个结构域都能有效地将二硫键引入未折叠的模型蛋白和肽中，但在处理折叠的底物蛋白分子时比PDI效率低。相对于PDI，这两个结构域在催化二硫键异构化方面均没有显著活性。这种活性模式与细菌催化剂DsbA非常相似，可能反映了这些蛋白质催化机制的相似性。PDI与其硫氧还蛋白样结构域之间的活性差异表明，PDI分子的其他特征对于其完整的硫醇-二硫键交换活性也是必需的。
