Kinetics of disaggregation, degradation and reactivation of α-glucosidase from inclusion bodies at various temperature. Cultures producing α-glucosidase in the wildtype strain with overexpression of ibpAB (black triangles, solid lines) or without (grey circles, dashed lines) and in the ibpAB deletion mutant (white squares, dotted lines) were incubated at 37°C to an OD600 of 0.5 and then induced with 1 mM IPTG. Two hours after induction, tetracycline was added to a final concentration of 25 μg mL-1, and the cultures were transferred to 15°C (A, E, I), 24°C (B, F, J), 30°C (C, G, K) or 37°C (D, H, L), respectively. Mean value and confidence interval of at least 2 (15 and 24°C) or 3–5 (30 and 37°C) independent experiments. Lines are from linear regression. (A-D) The amount of insoluble α-glucosidase was estimated by densitometry of Coomassie-stained SDS-PAGE gels and was referred to the value at the time of reactivation start (54 mg g-1 in the wildtype, 58 mg g-1 with overexpression of ibpAB and 49 mg g-1 in the deletion mutant). (E-H) α-Glucosidase activity and protein content were determined in cell extracts after disruption. Specific activity of α-glucosidase is given in units per mg of protein. (I-L) Degradational loss of α-glucosidase calculated as difference of the sum of soluble and insoluble α-glucosidase to the value obtained before addition of tetracycline. Time is given in hours after induction.