Publications

• The refolding of urea-denatured ribonuclease A is catalyzed by peptidyl-prolyl cis-trans isomerase.

  Fischer G., Bang H.

  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 ... >> More

  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. << Less

  Biochim Biophys Acta 828:39-42(1985) [PubMed] [EuropePMC]

• [Determination of enzymatic catalysis for the cis-trans-isomerization of peptide binding in proline-containing peptides].

  Fischer G., Bang H., Mech C.

  The rates of cis to trans interconversion of Glt-(Ala)n-Pro-Phe-4-nitroanilides (n = 1-3) were estimated by means of a two-step process with chymotrypsin as the trans-substrate cleaving activity. By the aid of this system, pig kidney and several other tissues contained demonstrable catalytic activ ... >> More

  The rates of cis to trans interconversion of Glt-(Ala)n-Pro-Phe-4-nitroanilides (n = 1-3) were estimated by means of a two-step process with chymotrypsin as the trans-substrate cleaving activity. By the aid of this system, pig kidney and several other tissues contained demonstrable catalytic activity against the cis to trans interconversion of the proline containing peptides. The active protein fraction was purified 38-fold from pig kidney cortex by ammonium sulfate precipitation and a series of column chromatographic techniques. Activity was detected against the cis to trans interconversion of Glt-Ala-Ala-Pro-Phe-4-nitroanilide to a different extent. No activity was found with Phe-Pro-4-nitroanilide. With respect to the substrate specificity, this enzyme must be classified as a peptidyl-prolyl cis-trans-isomerase. The enzyme was strongly inactivated by p-chloromercuribenzoate, sodium dodecylsulfate, Hg2+- and Cu2+-ions, but was not inhibited by metal chelators, diisopropylphosphorofluoridate and chlorotosylamidophenylbutane. The activity is abolished by incubation with trypsin. The enzyme is heat sensitive at 50 degrees C. The results presented in this paper suggest a new type of enzymes, characterized by catalytic activity against conformational interconversions. The possibility of the location of the enzyme on ribosomal particles is discussed. << Less

  Biomed Biochim Acta 43:1101-1111(1984) [PubMed] [EuropePMC]

• Peptidyl-prolyl cis-trans isomerase is the cyclosporin A-binding protein cyclophilin.

  Takahashi N., Hayano T., Suzuki M.

  Peptidyl-prolyl cis-trans isomerase (PPIase) catalyses the cis-trans isomerization of proline imidic peptide bonds in oligopeptides and has been shown to accelerate the refolding of several proteins in vitro. Its activity has been detected in yeast, insects and Escherichia coli as well as in mamma ... >> More

  Peptidyl-prolyl cis-trans isomerase (PPIase) catalyses the cis-trans isomerization of proline imidic peptide bonds in oligopeptides and has been shown to accelerate the refolding of several proteins in vitro. Its activity has been detected in yeast, insects and Escherichia coli as well as in mammals, and it is though to be essential for protein folding during protein synthesis in the cell. We purified PPIase from pig kidney and found that its amino-acid sequence is identical to that reported for bovine cyclophilin, a protein known to bind the immunosuppressive drug, cyclosporin A (ref. 5). To investigate the functional relationship between PPIase and cyclophilin we examined the effect of cyclosporin A on PPIase activity and found that it was inhibitory. Thus we propose that the peptidyl-prolyl cis-trans isomerizing activity of PPIase may be involved in events, such as those occurring early in T-cell activation, that are suppressed by cyclosporin A. << Less

  Nature 337:473-475(1989) [PubMed] [EuropePMC]

• Cyclophilin and peptidyl-prolyl cis-trans isomerase are probably identical proteins.

  Fischer G., Wittmann-Liebold B., Lang K., Kiefhaber T., Schmid F.X.

  The enzyme peptidyl-prolyl cis-trans isomerase (PPIase) was recently discovered in mammalian tissues and purified from porcine kidney. It catalyses the slow cis-trans isomerization of proline peptide (Xaa-Pro) bonds in oligopeptides and accelerates slow, rate-limiting steps in the folding of sever ... >> More

  The enzyme peptidyl-prolyl cis-trans isomerase (PPIase) was recently discovered in mammalian tissues and purified from porcine kidney. It catalyses the slow cis-trans isomerization of proline peptide (Xaa-Pro) bonds in oligopeptides and accelerates slow, rate-limiting steps in the folding of several proteins. Here, we report the N-terminal sequence of PPIase together with further chemical and enzymatic properties. The results indicate that this enzyme is probably identical to cyclophilin, a recently discovered mammalian protein which binds tightly to cyclosporin A (CsA). Cyclophilin is thought to be linked to the immunosuppressive action of CsA. The first 38 amino-acid residues of porcine PPIase and of bovine cyclophilin are identical and the two proteins both have a relative molecular mass of about 17,000 (ref. 7). The catalysis of prolyl isomerization in oligopeptides and of protein folding by PPIase are strongly inhibited in the presence of low levels of CsA. The activities of both PPIase and cyclophilin depend on a single sulphydryl group. At present it is unknown whether the inhibition of prolyl isomerase activity is related with the immunosuppressive action of CsA. << Less

  Nature 337:476-478(1989) [PubMed] [EuropePMC]