Comparative distribution of glutamyl and aspartyl aminopeptidase activities in mouse organs

To evaluate the functional role of glutamyl and aspartyl aminopeptidases, t heir soluble and membrane-bound activities were measured simultaneously in several tissues of normal mice using arylamide derivatives as substrates. A lthough the soluble aspartyl aminopeptidase activity showed its highest lev els in the testicle, the rest of the activities presented their highest lev els in the kidney. Different patterns of distribution were observed for glu tamyl and aspartyl aminopeptidase activities and also for soluble and membr ane-bound aspartyl aminopeptidase activities. However no major differences were observed between soluble and membrane-bound glutamyl aminopeptidase ac tivities. This unequal distribution suggests that the use of arylamide deri vatives as substrates is a sensitive method that distinguishes between thes e enzymatic activities. The results also suggest different functions for so luble and membrane-bound aspartyl aminopeptidase activities, and for glutam yl and aspartyl aminopeptidase activities.