Fig. 3

Bovine cathepsin K from the E. granulosus HCW, visualized on SDS-PAGE and by Western blot. The crude extracts and the peak active fractions from the resource Q anion exchange step and from the subsequent gel filtration step were run on SDS-PAGE (10% w/v acrylamide, reducing conditions) and either Coomassie-stained (A) or transferred to nitrocellulose and probed with antibodies to recombinant human cathepsin K (B), with antibodies to a C-terminal peptide of the enzyme (C), or with normal rabbit serum (not shown). For Coommassie staining, 20 µg (extracts and anion exchange fraction) or 6 µg of protein (gel filtration fraction) were loaded per track. For Western blotting, 7 µg (extracts) or 1 µg (gel filtration fraction) of protein were loaded per track; recombinant human cathepsin K (rec cath K; 1 µg) was included as a positive control. The 29-kDa and 40-kDa bands from the anion exchange peak fraction, which were subjected to N-terminal sequencing, are indicated in (A). Note that these correspond to the procathepsin K and cathepsin K bands detected by Western blotting (B). The control blot probed with normal rabbit serum gave no staining at all.