Aim: To identify the cathepsins in adult worms of Schistosoma japonicum and their proteolytic activities.
Methods: 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.
Results: 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.
Conclusion: The vomitus of S. japonicum has cathepsin B- and L-like activity.