Scholz C, Maier P, Dolinski K, Heitman J, Schmid F X
Biochemisches Laboratorium, Universität Bayreuth, Germany.
FEBS Lett. 1999 Jan 29;443(3):367-9. doi: 10.1016/s0014-5793(98)01735-9.
Previously we reported that the R73A and H144Q variants of the yeast cyclophilin Cpr3 were virtually inactive in a protease-coupled peptide assay, but retained activity as catalysts of a proline-limited protein folding reaction [Scholz, C. et al. (1997) FEBS Lett. 414, 69-73]. A reinvestigation revealed that in fact these two mutations strongly decrease the prolyl isomerase activity of Cpr3 in both the peptide and the protein-folding assay. The high folding activities found previously originated from a contamination of the recombinant Cpr3 proteins with the Escherichia coli protein SlyD, a prolyl isomerase that co-purifies with His-tagged proteins. SlyD is inactive in the peptide assay, but highly active in the protein-folding assay.
此前我们报道，酵母亲环蛋白Cpr3的R73A和H144Q变体在蛋白酶偶联肽分析中实际上无活性，但作为脯氨酸限制的蛋白质折叠反应的催化剂仍保留活性[Scholz, C.等人(1997年)《欧洲生物化学学会联合会快报》414, 69 - 73]。重新研究发现，实际上这两个突变在肽和蛋白质折叠分析中均强烈降低了Cpr3的脯氨酰异构酶活性。先前发现的高折叠活性源于重组Cpr3蛋白被大肠杆菌蛋白SlyD污染，SlyD是一种与His标签蛋白共纯化的脯氨酰异构酶。SlyD在肽分析中无活性，但在蛋白质折叠分析中高度活跃。
