Biochemical and immunological studies of angiotensin converting enzymes from human, bovine, dog, hog, rabbit, rat and sheep kidneys.

1. Molecular and kinetic properties of angiotensin converting enzymes from seven different species' kidneys were similar concerning apparent molecular weight, heat sensitivity, Km value, optimum pH, activation by chloride ion, and inhibition by specific converting enzyme inhibitors (captopril and SA 446). 2. Rabbit antibody against pure human kidney enzyme cross-reacted partially with each animal kidney enzyme except for the rabbit enzyme. Antigenic determinants of animal enzymes were variable from species to species and differed from those of the human enzyme in extent and specificity.