[Studies on cathepsins in Schistosoma japonicum]

To identify the cathepsins in adult worms of Schistosoma japonicum and their proteolytic activities.

The vomitus from adult worms of S. japonicum was collected. The proteolytic activity of cathepsins in the vomitus was identified and measured using synthetic substrates with arginyl bonds.

Specific synthetic subtracts Z-Arg-Arg-AMC (for cathepsin B) and Z-Phe-Arg-AMC (for cathepsin B and L) were degraded by the vomitus. An inhibitor, Z-Phe-PheCHN2 for cathepsin L, inhibited partially the activity of the vomitus to degrade Z-Phe-Arg-AMC. The optimal pH for cathepsin B/L is 5.0-5.5.

The vomitus of S. japonicum has cathepsin B- and L-like activity.