Figure 6. F508del-CFTR folding assay.

Proteins were denatured and renatured in a test tube at 37°C resulting in the formation of large sized aggregates whose formation was monitored by an increase in turbidity at 405 nm. F508del-CFTR aggregation was observed to follow a typical ‘S-curve’. Addition of calumenin to the reaction mixture was observed to reduce F508del aggregation by ∼33%. 2 mM calcium further reduced aggregation substantially by ∼83%. In contrast, 0.75 mM calcium was observed to promote aggregation (by ∼44%). Further addition of MgATP, reduced F508del-CFTR aggregation by ∼75% (for 0.75 mM calcium) and ∼86% (for 2 mM calcium). Calumenin with EDTA had the maximum effect (∼92% reduction) in reducing aggregation. AavLEA1, and IDP, prevented F508del-CFTR aggregation at early time points. Bovine serum albumin (BSA) was used as a negative control in our reactions.