Ferrer M, Barany G, Woodward C
Department of Chemistry, University of Minnesota, Minneapolis 55455, USA.
Nat Struct Biol. 1995 Mar;2(3):211-7. doi: 10.1038/nsb0395-211.
Three denatured states of bovine pancreatic trypsin inhibitor have been characterized, using two chemically synthesized analogues designed for study of folding intermediates. One analogue, [14-38]Abu, retains only the 14-38 disulphide. At pH 4.5-6 and 1-7 degrees C, [14-38]Abu is a highly ordered beta-sheet molten globule; it has the circular dichroism (CD), ANS-binding and folding kinetics of a molten globule; is partially folded by NMR analysis; and undergoes cooperative thermal denaturation. At low temperature [14-38]Abu also forms an acid state at pH 1.5, as well as a denatured state at pH 2.5. A second BPTI analogue with all three disulphide bridges eliminated, [R]Abu, lacks detectable secondary and tertiary structure but has stable hydrophobic surfaces and is collapsed. We term this species a 'molten coil'.
利用两种为研究折叠中间体而设计的化学合成类似物，已对牛胰蛋白酶抑制剂的三种变性状态进行了表征。一种类似物[14-38]Abu仅保留14-38二硫键。在pH 4.5 - 6和1 - 7摄氏度条件下，[14-38]Abu是一种高度有序的β-折叠熔球；它具有熔球的圆二色性（CD）、ANS结合特性和折叠动力学；通过核磁共振分析部分折叠；并经历协同热变性。在低温下，[14-38]Abu在pH 1.5时还形成一种酸性状态，在pH 2.5时形成变性状态。第二种消除了所有三个二硫键的BPTI类似物[R]Abu缺乏可检测到的二级和三级结构，但具有稳定的疏水表面且呈塌陷状态。我们将这种物质称为“熔线圈”。
