Spontaneous Re-formation of a Broken Peptide Chain
Spontaneous Re-formation of a Broken Peptide Chain
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断裂肽链的自发重组
作者：
D. Dyckes;T. Creighton;R. Sheppard
碱性胰蛋白酶抑制物(BPTI)是一种由58个氨基酸残基组成的蛋白质，对丝氨酸蛋白酶、胰凝乳酶、纤溶酶和激肽释放酶具有抑制作用。序列已被完全阐明1(图1)，三维结构已被X射线结晶学测定到高分辨率2，3。结合用于蛋白质折叠研究的BPTI类似物的部分合成的研究，我们详细地研究了溴化氰对蛋白质的切割作用。我们发现，链断裂的产物是不稳定的，站立时，它会自发转化为含有58个氨基酸残基的完整链的BPTI类似物。
BASIC pancreatic trypsin inhibitor (BPTI) is a protein of fifty-eight amino acid residues, which inhibits the serine proteinases trypsin, chymotrypsin, plasmin and kallikrein. The sequence has been fully elucidated1 (Fig. 1) and the three-dimensional structure has been determined to high resolution by X-ray crystallography2,3. In connection with studies on the partial synthesis of analogues of BPTI for the investigation of protein folding, we have examined in detail cleavage of the protein by cyanogen bromide4. We have found that the chain-cleaved product is unstable, and that on standing it is spontaneously transformed into an analogue of BPTI containing an intact chain of fifty-eight amino acid residues.