ANALYSIS OF CATHEPSIN-D FROM BREAST TISSUES BY CAPILLARY ELECTROPHORESIS

A rapid and simple method for analyzing cathepsin D in breast tissue b ased on capillary zone electrophoresis (CZE) is described. After incub ating the tissue extracts with hemoglobin as a substrate, a specific p eptide is cleaved and separated by CZE in less than 5 min. This peptid e is not produced by the action of pepsin or trypsin. II is inhibited by the addition of pepstatin, a specific inhibitor for cathepsin D. Hu man hemoglobin acted as a better substrate than bovine hemoglobin. The test compared well to a radioimmunoassay. We have shown that peptides can be stacked by the use of acetonitrile. The method demonstrates th e advantages of CZE for assay of proteolytic enzymes in general.