PPIase that catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides and may therefore assist protein folding (PubMed:20676357). May be involved in pre-mRNA splicing (PubMed:11991638). {ECO:0000269|PubMed:11991638, ECO:0000269|PubMed:20676357}. This is the function of Ensembl gene identifier ENSG00000113593 (PPWD1, peptidylprolyl isomerase domain and WD repeat containing 1).