Catalyzes the cis-trans isomerization of peptidyl prolyl bonds and accelerates protein folding. Also exhibits chaperone-like activity (PubMed:10824098). In vitro, can use oligopeptides such as N-succinyl-Ala-Leu-Pro-Phe-p-nitroanilide and N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide as substrates. The PPIase activity is much lower than those of other FKBPs reported against oligopeptidyl substrates. As a chaperone, protects green fluorescent protein (GFP) and rhodanese from thermal denaturation or aggregation, and suppresses the aggregation of chemically unfolded rhodanese and elevates the yield of its refolding (PubMed:10824098). [protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0) Homohexamer. Contains an N-terminal PPIase domain, an IF (Insert in the Flap) domain and a C-terminal domain (CTD). Aggregation suppressing activity against chemically unfolded protein is exerted mainly by the CTD while N- and C-terminal domains contribute to thermal protein aggregation suppression. The CTD probably contributes to hexamerization. Belongs to the FKBP-type PPIase family.