PPIases accelerate the folding of proteins (Probable). It catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides (PubMed:2190212). [protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0) Inhibition by cyclosporin A with a Ki of 25 to 50 mu-mol, a concentration 1000-fold higher than that required for eukaryotic PPIases. Belongs to the cyclophilin-type PPIase family.