Abstract
Cathepsin D was purified by 2-step affinity chromatography on concanavalin A- and pepstatin-Sepharose. The main purification was achieved by washing the enzyme bound to the pepstatin-Sepharose column with buffered 6 M-urea. This step separated cathepsin D from all low and high MW impurities. Although the 1700-fold purified acid proteinase was homogeneous on sodium dodecyl sulfate/polyacrylamide-gel electrophoresis, it still showed microheterogeneity.