Figure 8.

Effect of temperature on thermal aggregation of activase in tobacco chloroplasts. Intact tobacco chloroplasts were incubated for 10 min at the indicated temperatures and then lysed with detergent in the presence of rhodanese. After 5 min at 23°C, aggregated protein was collected by centrifugation and separated by SDS-PAGE. Proteins in the soluble portion of the extracts were also separated by SDS-PAGE after diluting 3-fold. A, Activase in the aggregates (P) and in the soluble fractions (S) was visualized by immunoblotting. B, Total proteins in the aggregates were visualized by staining with Coomassie Brilliant Blue. The arrows labeled A and Rdn indicate the position of rhodanese (33.3 kD) and activase (42 kD) on the blots. The 42-kD polypeptide that was submitted for sequencing is indicated by the arrowhead.