Human spleen cathepsin D: its characterization and localization in human spleen

1. The cathepsin D was purified 1830-fold under mild conditions by a rapid procedure, based on two-step affinity chromatography. 2. Its molecular weight, amino acid composition and substrate specificity were shown to display minor differences from materials of other origins. 3. Inhibition with thiol compounds was found to be a specific phenomenon of the cathepsin D from the human spleen. 4. Production of antiserum specific for purified cathepsin D was demonstrated by immunodiffusion test, an immunoadsorbent column and immunoblotting of the crude enzyme in SDS gel. 5. In an immunocytochemical study, the antigenic sites for this enzyme were found to be localized in the reticuloendothelial system of the human spleen. 6. The role of this enzyme in human spleen cell was discussed.