Abstract
Two urinary enzymes that cleave alpha-N-p-tosyl-L-arginine methyl ester (TAMe) have been separated and utilized to elicit monospecific antisera; only one, urinary kallikrein (urokallikrein), had kinin-generating activity. The nonkinin-generating TAMe esterase and urokallikrein were antigenically unrelated. Immunoperoxidase studies of normal human kidney revealed localization of nonkinin-generating TAMe esterase to epithelial cells of the distal tubule, including the ascending thick limb, the macula densa region, and some areas of convoluted tubule. Immunoreactivity for urokallikrein was confined to reabsorption droplets of proximal tubules and to focal segments of the distal convoluted tubules. Electrophoretic, antigenic, and immunohistochemical studies have established that urokallikrein and a nonkinin-generating TAMe esterase represent two distinct renal distal tubule enzymes.