Catalyzed and assisted protein folding of ribonuclease T1

The small single-domain protein ribonuclease T1 (RNase T1) and variants thereof are good substrates for investigating the mechanisms of catalyzed and assisted protein folding. RNase T1 contains two cis prolines and two disulfide bonds, and the kinetic mechanism of its folding is well known. The wild-type form and designed variants that differ in the number prolines and of disulfide bonds were used as substrates to study the catalysis of folding by prolyl isomerases and protein disulfide isomerases. In its unfolded form, a marginally stable variant of RNase T1 binds to the chaperone GroEL and could thus be used to elucidate the kinetic mechanism of GroEL-mediated protein unfolding.