title: Prolyl isomerases do not catalyze isomerization of non-prolyl peptide bonds.
abstract: Prolyl isomerases accelerate the cis <--> trans isomerization of prolyl peptide bonds during protein folding and probably also in folded proteins. We asked whether this catalytic function is in fact restricted to prolyl bonds or whether the isomerizations of 'normal' non-prolyl peptide bonds are catalyzed as well. By using the P39A variant of ribonuclease T1 as a substrate we find that the trans --> cis isomerization of the Tyr38-Ala39 bond in the refolding of this protein is not catalyzed by prolyl isomerases of the cyclophilin, FKBP and parvulin families. These enzymes are neither able to catalyze amide bond isomerizations in the proline-free model peptide Ala-Ala-Tyr-Ala-Ala.
authors.affiliation: Laboratorium für Biochemie, Universität Bayreuth, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Scholz
authors.forename: G
authors.initials: G
authors.lastname: Scherer
authors.forename: L M
authors.initials: LM
authors.lastname: Mayr
authors.forename: T
authors.initials: T
authors.lastname: Schindler
authors.forename: G
authors.initials: G
authors.lastname: Fischer
authors.forename: F X
authors.initials: FX
authors.lastname: Schmid
mesh_terms: D000577:Amides / Q000737:chemistry; D002384:Catalysis; D007536:Isomerism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D019696:Peptidylprolyl Isomerase / Q000378:metabolism*; D017510:Protein Folding; D006163:Ribonuclease T1 / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D000577:Amides; D010455:Peptides; D006163:Ribonuclease T1; D019696:Peptidylprolyl Isomerase