Folding of barstar C40A/C82A/P27A and catalysis of the peptidyl‐prolylcis/transisomerization by human cytosolic cyclophilin (Cyp18)

Abstract
Refolding of b*C40A/C82A/P27A is comprised of several kinetically detectable folding phases. The slowest phase in refolding originates fromtrans → cisisomerization of the Tyr47–Pro48 peptide bond being incisconformation in the native state. This refolding phase can be accelerated by the peptidyl‐prolylcis/transisomerase human cytosolic cyclophilin (Cyp18) with akcat/KMof 254, 000 M–1s–1. The fast refolding phase is not influenced by the enzyme.