Compounds and methods for detecting tripeptidyl protease I

The present invention provides compounds useful for the detection of the enzyme tripeptidyl protease I (TPP-1). The invention also provides methods of making such compounds, methods of using such compounds, and kits and compositions containing such compounds. In one embodiment, Gly-L-Pro-L-Ser-1-anthraquinonylhydrazide, in combination with p-anisaldehyde, is used to detect TPP-1.