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R73A and H144Q mutants of the yeast mitochondrial cyclophilin Cpr3 exhibit a low prolyl isomerase activity in both peptide and protein‐folding assays
Author(s) -
Scholz Christian,
Maier Peter,
Dolinski Kara,
Heitman Joseph,
Schmid Franz X
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01735-9
Subject(s) - prolyl isomerase , peptidylprolyl isomerase , peptide , biochemistry , isomerase , yeast , protein folding , cyclophilin , protein disulfide isomerase , chemistry , mutant , folding (dsp implementation) , recombinant dna , biology , enzyme , pin1 , electrical engineering , gene , engineering
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.