Z-Ala-Pro-pNA is an endopeptidase substrate and can be used to detect the activity of this enzyme[1].
References
[1] Abbott CA, et al. Cloning, expression and chromosomal localization of a novel human dipeptidyl peptidase (DPP) IV homolog, DPP8. Eur J Biochem. 2000 Oct;267(20):6140-50. DOI:10.1046/j.1432-1327.2000.01617.x
