[Multiple forms of cathepsin D from the human brain]

Six peaks of the endopeptidase activity at pH 3.2 were obtained after isoelectric focusing of soluble fractions of cortex and hypothalamus of the human brain. The molecular weight of these endopeptidases are approximately 50000. All obtained endopeptidases possess almost the same Km and I50 relative to the substrate--pyridoxal globin and specific inhibitor--pepstatin. The studies of the revealed properties show that the endopeptidases are multiple forms of cathepsin D.