Histochemical Demonstration of Tripeptidyl Aminopeptidase I

Enzyme histochemical methods are valuable for the studies on the enzyme involvement in different pathological processes. Here we describe two protocols for chromogenic and fluorogenic histochemical demonstration of tripeptidyl aminopeptidase I (TPPI), a protease that is crucial for neuronal functions. The procedures are based on newly synthesized substrates for TPPI-glycyl-L-prolyl-L-metionyl-5-chloro-1-anthraquinonylhydrazide (GPM-CAH) and glycyl-L-prolyl-L-metionyl-4-hydrazido-N-hexyl-1,8-naphthalimide (GPM-HHNI). Using such protocols, precise enzyme localization can be obtained in tissue sections of mammalian organs.