van Mierlo C P, Darby N J, Neuhaus D, Creighton T E
MRC Laboratory of Molecular Biology, Cambridge, England.
J Mol Biol. 1991 Nov 20;222(2):373-90. doi: 10.1016/0022-2836(91)90217-t.
An analogue of the bovine pancreatic trypsin inhibitor (BPTI) folding intermediate that contains only the disulphide bond between Cys5 and Cys55 has been prepared in Escherichia coli by protein engineering methods, with the other four Cys residues replaced by Ser. Two-dimensional 1H nuclear magnetic resonance studies of the analogue have resulted in essentially complete resonance assignments of the folded form of the protein. The folded protein has a compact conformation that is structurally very similar to that of native BPTI, although there are subtle differences and the folded conformation is not very stable. Approximately half of the protein molecules are unfolded at 3 degrees C, and this proportion increases at higher temperatures. The folded and unfolded conformations are in slow exchange. The conformational properties of the analogue can explain many aspects of the kinetic role that the normal (5-55) intermediate plays in the folding of BPTI.
通过蛋白质工程方法在大肠杆菌中制备了一种牛胰蛋白酶抑制剂（BPTI）折叠中间体的类似物，该类似物仅含有Cys5和Cys55之间的二硫键，其他四个半胱氨酸残基被丝氨酸取代。对该类似物进行的二维¹H核磁共振研究已基本完成了该蛋白质折叠形式的共振归属。折叠后的蛋白质具有紧密的构象，其结构与天然BPTI非常相似，尽管存在细微差异且折叠构象不太稳定。大约一半的蛋白质分子在3摄氏度时未折叠，并且这一比例在较高温度下会增加。折叠态和未折叠态处于缓慢交换状态。该类似物的构象特性可以解释正常（5-55）中间体在BPTI折叠过程中动力学作用的许多方面。
