FIG. 8.

Digestion of CIII by trypsin. (A) CIII was digested by trypsin for 1 to 30 min as indicated and then analyzed by 18% SDS-PAGE. Lane U shows the undigested protein. The positions of CIII and the tryptic fragments CIIIA and CIIIB are indicated. (B) Sequence of CIII with the possible tryptic sites marked (underlined). The 20 N-terminal residues in this sequence make up the histidine tag. Possible cleavage fragments between 5.5 kDa and 7 kDa are shown below as boxes. The calculated molecular mass is shown on the right, and the terminal residue numbers for each fragment are shown on the left.