title: The refolding of urea-denatured ribonuclease A is catalyzed by peptidyl-prolyl cis-trans isomerase.
abstract: The refolding of urea-denatured ribonuclease A was measured at 0.31-3.1 mol . l-1 urea in the presence of various concentrations of peptidyl-prolyl cis-trans isomerase isolated from pig kidney. The rate of the slow CT-phase in the refolding reaction was found to be sensitive to this enzyme. A rate enhancement proportional to the isomerase activity has been observed. The activity of the enzyme was assayed with Glt-Ala-Ala-Pro-Phe-4-nitroanilide. The catalytic activity of the isomerase against unfolded ribonuclease is suppressed after preincubation of the enzyme with 0.001 mol . l-1 Cu2+, 0.01 mol . l-1 H+ and by heat inactivation. The results indicate the involvement of the cis/trans interconversion of proline peptide bonds during the refolding of ribonuclease A.
mesh_terms: D000591:Amino Acid Isomerases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D003300:Copper / Q000494:pharmacology; D007668:Kidney / Q000201:enzymology; D007700:Kinetics; D019696:Peptidylprolyl Isomerase; D011487:Protein Conformation; D011489:Protein Denaturation; D012260:Ribonucleases / Q000378:metabolism*; D013552:Swine; D014508:Urea / Q000494:pharmacology
chemical_list: D003300:Copper; D014508:Urea; D012260:Ribonucleases; D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase