Diagnostic application of AAP isoenzyme separation

We describe the separation of alanylaminopeptidase (AAP) from urine into two isoenzymes: a particulate and a soluble form. The separation was accomplished using ion-exchange column chromatography on DEAE-52 cellulose. The purity of the isolated forms was confirmed electrophoretically. We attempted to create a method allowing the quantitative assessment of AAP isoenzymes in urine based on electrophoretic separation in 7.5% polyacrylamide gel with subsequent densitometric analysis. The content of AAP isoenzymes in examined urine was estimated using ultracentrifugation. The differences in the content of cytosolic and microsomal forms were observed suggesting the possibilities of using AAP isoenzymes in diagnostics. Furthermore, the effect of temperature on the activity of AAP separated on DEAE-52 cellulose was studied.