FIGURE 1.

Autoprocessing of cathepsin K is promoted by acidic pH and chondroitin 4-sulfate. A, cleavage of the pro-domain from pro-hrCatK (4 μm) to mature enzymes was evaluated in buffers with pH ranging from 4.0 to 7.5 without (top panel) and with (bottom panel) 18 μm C4-S. The reaction mixture was incubated at 37 °C for 3 h in 100 mm of pH buffers containing 100 mm NaCl and 1 mm CaCl₂. B, processing of the pro-domain from wild type pro-hrCatK(WT) was compared with that from the pro-forms of hrCatK mutants (as described under “Experimental Procedures”) and wild type human pro-CatK (pro-hCatK(WT)) at pH 5.0.