As described by Botelho et al. [6], 100 g of E. coli proteome extract was loaded onto each of four 6 mm i.d., 12% T gel columns. A voltage of 250 V was applied and a total of 15 fractions were collected, according to the following time scheme: dye front (fraction 0), 5 × 1 min, 5 × 2 min, 3 × 5 min, 1 × 15 min. Fractions from a given collection interval were pooled across the four columns. The combined fractions were visualized by SDS-PAGE with coomassie staining. Fractions 4 + 5 (MW 30–45 kDa) and fractions 12 + 13 (55–80 kDa) were then combined to form the low mass and high
mass fractions, respectively (total volume of each fraction ∼800 L)