[Purification and properties of thiol-activated cathepsin from bovine cerebrum and cerebellum].

Thiol-activated cathepsin was isolated from bovine cerebral hemispheres and cerebellum. The enzyme from the hemispheres was purified by the affinity sorbent chromatography method with the sepharose-4B-immobilized protein substrate, azocasein, and with subsequent separation of nonspecifically sorbed protein by column gel-chromatography on Sephadex G-100. The cathepsin pH-optimum was 6.0. The coincidence in cellular (neuron and glia enriched fractions) and subcellular distribution of cathepsin D and thiol-activated cathepsin activities shows the probable lysosomal origin of the latter. The data obtained about the influence of the various proteolytic enzyme inhibitors and activators on the thiol-activated cathepsin activity show a definite similarity of the enzyme with the thiol proteinases of the rat liver lysosomes, cathepsin B1 and L.