Protein Folding and SDS-PAGE Analysis

Samples were folded under the same conditions as folding titrations as previously described^{6 (link), 16} . Final folded samples contained 1 M GdnHCl, 20 mM tris(hydroxymethyl)aminomethane (TRIS), 2 mM ethylenediaminetetraacetic acid (EDTA), 0.4 µM protein and a 2000:1 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) ratio. Because GdnHCl precipitates in sodium dodecyl sulfate (SDS), samples were dialyzed in Slide-A-Lyzer cassettes with a 3.5 kDa molecular weight cut-off (Pierce) into 20 mM TRIS, 2 mM EDTA overnight at room temperature. Samples were then concentrated with 0.5 mL with PES spin concentrators with a 10 kDa molecular weight cutoff (Pierce) to a final concentration of 4 µM protein. SDS-PAGE was performed as in¹⁷ using 12% Mini-Protean TGX pre-cast gels (Bio-Rad). The ladder used was PageRuler pre-stained 10 to 180 kDa (Thermo).