Figure 3.

SDS–PAGE profile of 1C1 Fab (lanes 1 and 4), rEphA2 (lanes 2 and 5) and a dissolved crystal of the 1C1 Fab–rEphA2 crystal complex (lanes 3 and 6) under reducing and nonreducing conditions. The 4–20% gradient gel (Bio-Rad, Hercules, California, USA) was stained with Bio-Safe Coomassie Stain (Bio-Rad). It shows rEphA2 migrating at around 15 and 19 kDa under nonreducing and reducing conditions, respectively. This difference is likely to be attributable to the presence of two internal disulfide bonds, the reduction of which alters the compactness (and thus the migration) of the molecule. The same argument can be applied to the 1C1 Fab fragment, which migrated slightly under its expected molecular weight of 50 kDa at around 45 kDa under nonreducing conditions. As expected, its heavy and light chains both migrated at 25 kDa under reducing conditions.