Song J, Quan H, Wang C
National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing 100101, China.
Biochem J. 1997 Dec 15;328 ( Pt 3)(Pt 3):841-6. doi: 10.1042/bj3280841.
Protein disulphide isomerase (PDI) shows chaperone and anti-chaperone activities in assisting refolding of denatured and reduced lysozyme in redox Hepes buffer, but only chaperone activity in phosphate buffer and redox Hepes buffer containing 0.1 M NaCl. In non-redox Hepes buffer its anti-chaperone activity is very weak. PDI displays its anti-chaperone activity only for those substrates showing relatively low aggregation during refolding, and is strongly dependent on refolding conditions, of which ionic strength appears to be an important factor. The S-methylated PDI, fully active as a chaperone but devoid of isomerase activity, by itself shows only anti-chaperone activity, but reinforces rather than suppresses the chaperone activity of native PDI in the refolding of lysozyme. A fragment of PDI with the C-terminal peptide-binding sequence removed and devoid of chaperone activity does not show anti-chaperone activity in lysozyme refolding. It appears that the anti-chaperone activity of PDI is dependent on its chaperone activity.
蛋白质二硫键异构酶（PDI）在氧化还原Hepes缓冲液中协助变性和还原的溶菌酶重折叠时表现出伴侣和抗伴侣活性，但在磷酸盐缓冲液以及含有0.1 M NaCl的氧化还原Hepes缓冲液中仅表现出伴侣活性。在非氧化还原Hepes缓冲液中，其抗伴侣活性非常弱。PDI仅对那些在重折叠过程中聚集程度相对较低的底物表现出抗伴侣活性，并且强烈依赖于重折叠条件，其中离子强度似乎是一个重要因素。S-甲基化的PDI作为伴侣完全有活性但缺乏异构酶活性，其本身仅表现出抗伴侣活性，但在溶菌酶重折叠过程中增强而非抑制天然PDI的伴侣活性。去除了C端肽结合序列且缺乏伴侣活性的PDI片段在溶菌酶重折叠过程中不表现出抗伴侣活性。看来PDI的抗伴侣活性依赖于其伴侣活性。
