Figure 4.

Comparison of the crowding effects of Ficoll 70 and dextran 70. (A) Rhodanese refolding at increasing concentrations of Ficoll 70 or dextran 70 in the presence of an 8-fold molar excess of GA-GroEL over wild-type GroEL. Rhodanese activities measured upon refolding in the presence of crowding agent and in the absence of trap-GroEL are set to 100%. The enzyme activity regained in the absence of trap-GroEL at a 30% concentration of either crowding agent was ≈80% of that measured in buffer. (B) Relationship between the viscosity of solutions containing crowding agent and their ability to suppress trapping during refolding reactions. Shown is the efficiency by which an 8-fold molar excess of trap-GroEL captures rhodanese during GroEL/GroES-mediated refolding in 30% Ficoll 70 (left) and in 20% dextran 70 (right). The relative viscosities of the crowding agents at the respective concentrations also are displayed. Viscosities relative to buffer were determined based on the Poiseuille method with an Ostwald dropping pipet at 25°C.