Catalysis of RNase T1 refolding reaction by antibody 47 Mar.1. The change in fluorescence at 320 nm is shown as a function of the time. The final conditions for refolding were 3.0 μM RNase T1 in 0.2 M urea, 0.1 M Tris⋅HCl, 1 mM EDTA, pH 8.0 at 10 ± 0.1°C. Uncatalyzed folding reaction in the absence of a catalyst (▴); folding reactions in the presence of 6.4 μM antibody 47 Mar.1 (▵), 6.4 μM antibody, and an additional hapten 1: 3.7 μM (◊) and 9.1 μM (○), and 0.14 μM FKBP (•).