PPIases accelerate the folding of proteins. It catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides (By similarity). [protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0) In the N-terminal section; belongs to the HAD-like hydrolase superfamily. Cof family. In the C-terminal section; belongs to the cyclophilin-type PPIase family. PPIL1 subfamily.