Analysis of protein folding memory with modification of intramolecular chaperons and its application

利用酵母细胞表面展示的方法，成功地将前肽突变的羧肽酶Y（CPYs）展示在酵母细胞表面，并通过选择性切割突变前肽的方法纯化了成熟酶。所展示的CPY的活性和动力学的测量表明，前肽突变改变了mCPY的催化效率。尽管野生型和突变体CPY的成熟区具有相同的氨基酸序列，但来自突变体proCPY的mCPY具有比野生型更高的催化效率。这些结果表明，具有相同氨基酸序列的蛋白质可以通过突变的分子内伴侣折叠成具有微观构象变化的异构蛋白质。

CPYs (carboxypeptidase Y) with mutated propeptides were successfully displayed on yeast cell surface, and the mature enzymes were purified by the selective cleavage of mutated propeptides. Measurement of the activity and kinetics of the displayed CPYs indicated that the propeptide mutation altered the catalytic efficiency of mCPY. Although the mature region of the wild -type and mutant CPYs had identical amino acid sequences, the mCPYs from the mutant proCPYs had higher catalytic efficiency than the wild-type. These results indicate that proteins with identical amino acid sequence can fold into isomeric proteins with micro-conformational changes through mutated intramolecular chaperones.