The DPPIV-Glo Protease Assay is a homogeneous, luminescent assay that measures dipeptidyl peptidase IV (DPPIV) activity. DPPIV is a serine protease that cleaves N-terminal dipeptides from polypeptides with L-proline or L-alanine at the penultimate position. The DPPIV-Glo Assay provides a proluminescent DPPIV substrate, Gly-Pro-aminoluciferin, in a buffer system optimized for DPPIV and luciferase activities. The addition of a single DPPIV-Glo Reagent in an add-mix-measure format results in DPPIV cleavage of the substrate and generation of a glow-type luminescent signal produced by the luciferase reaction. In this homogeneous, coupled-enzyme format, the signal is proportional to the amount of DPPIV activity present. The assay is designed for use with purified enzyme preparations.