FIGURE 3.

Limited proteolysis of purified KptA. Reaction mixtures (20 μL) containing 10 mM Tris-HCl (pH 8.0), 5 μg of KptA, and 1.6, 3.2, 6.2, or 12.5 ng of trypsin (from left to right) were incubated for 15 min at 22°C. Trypsin was omitted from the control mixture shown in lane –. The reactions were quenched by adding SDS and the digests were resolved by SDS-PAGE. The Coomassie Blue-stained gel is shown. A duplicate gel was electroblotted to PVDF; intact His₁₀-Tpt1 and individual tryptic products were subjected to automated Edman sequencing; their sequences are indicated in single-letter code (right).