Determination of Cathepsins D and E in Various Tissues and Cells of Rat, Monkey, and Man by the Assay with β-Endorphin and Substance P as Substrates

Abstract

We developed a new method for the assay of cathepsins D and E. The method was based on the different hydrolytic activities of cathepsins D and E against β-endorphin and substance P. The method was applied to the determination of the levels of cathepsins D and E in various tissues and cells of rat, monkey, and man, and was clarified to be much more specific, sensitive, and quantitative than the ordinary hemoglobin-digestion method. The levels of cathepsin D were high in adrenal and spleen, and the levels of cathepsin E were high in gastrointestinal tissues, bone marrow, and lymph node. The variations in level were much wider in the case of cathepsin E than in the case of cathepsin D. This might reflect that cathepsin D is a house-keeping lysosomal enzyme in a variety of cells and cathepsin E is involved in the physiological activities of certain types of tissues and cells.