Analysis of PDI- and PPI-assisted folding of α-GI. Oxidative folding studies were performed in the presence of 0.1 mm GSH, 0.1 mm GSSG, and 20 μm linear peptide with and without Conus PDI and/or PPI. Folding reactions were acid-quenched at 0, 4, 8, 16, 32, and 64 min and analyzed by reversed-phase chromatography. A, relative abundance of the fully folded, globular peptide was determined by reversed-phase chromatography as shown in B and plotted against time points of folding. Plotted values are averages from three independent experiments (mean ± S.D. (error bars)). B, reversed-phase chromatograms of folding reactions quenched after 16 min. White circles denote the folded, globular peptide as determined by its characteristic elution profile (27, 29) and co-elution experiments.