Premium
Cyclophilin active site mutants have native prolyl isomerase activity with a protein substrate
Author(s) -
Scholz Christian,
Schindler Thomas,
Dolinski Kara,
Heitman Joseph,
Schmid Franz X.
Publication year - 1997
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(97)00979-4
Subject(s) - isomerase , prolyl isomerase , cyclophilin , biochemistry , active site , chemistry , peptidylprolyl isomerase , tetrapeptide , foldase , proteolysis , mutant , zymogen , triosephosphate isomerase , enzyme , stereochemistry , peptide , pin1 , escherichia coli , groel , gene
The prolyl isomerase activity of cyclophilins is traditionally measured by an assay in which prolyl cis / trans isomerization in a chromogenic tetrapeptide is coupled with its isomer‐specific cleavage by chymotrypsin. Two variants of mitochondrial cyclophilin with substitutions in the presumed active site (R73A and H144Q) are inactive in the protease‐coupled assay, but show almost wild‐type activity in an assay that is based on the catalysis of a proline‐limited protein folding reaction. This prolyl isomerase assay is preferable, both because coupling with proteolysis is avoided and because an intact protein instead of a short peptide is used as a substrate. Possibly, some earlier conclusions about the catalytic mechanism and the involvement of the prolyl isomerase activity in the cellular function of immunophilins may need reevaluation.