Fig. 4. Partial proteolysis of wild-type and mutant ParA proteins. ParA protein (2.5 µg per lane) was incubated with or without trypsin in 25 mM HEPES–KOH pH 7.5, 200 mM NaCl, 5 mM MgCl₂, 5% (v/v) glycerol, 0.05 mM Na₂EDTA, 0.5 mM dithiothreitol for 4 h at room temperature, and then analyzed by electrophoresis in a 15% SDS–polyacrylamide gel. In each set of four lanes, the ratio (w/w) of trypsin to ParA was 0, 1:200, 1:100 and 1:50. The numbers at the left show the size (in kDa) of the molecular size markers in the first lane.