DETERMINATION OF CATHEPSIN-D AND CATHEPSIN-E IN VARIOUS TISSUES AND CELLS OF RAT, MONKEY, AND MAN BY THE ASSAY WITH BETA-ENDORPHIN AND SUBSTANCE-P AS SUBSTRATES

We developed a new method for the assay of cathepsins D and E. The met hod was based on the different hydrolytic activities of cathepsins D a nd E against beta-endorphin and substance P. The method was applied to the determination of the levels of cathepsins D and E in various tiss ues and cells of rat, monkey, and man, and was clarified to be much mo re specific, sensitive, and quantitative than the ordinary hemoglobin- digestion method. The levels of cathepsin D were high in adrenal and s pleen, and the levels of cathepsin E were high in gastrointestinal tis sues, bone marrow, and lymph node. The variations in level were much w ider 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 ac tivities of certain types of tissues and cells.