A comparison of the kallikrein-kinin system in sheep and dogs

Three preparations of kallikrein, made from the urine of man, dog and sheep, all formed active kinins when incubated with the plasma of sheep or dogs. The six kinins could not be distinguished from one another by parallel assays on guinea-pig ileum, rat uterus and rat duodenum; they are thought to be identical, or nearly so. As judged by the amount of kinin produced, a sample of dog plasma appeared to contain about 4.3 times as much substrate as a sample of sheep plasma. This ratio did not depend on the kallikrein used. Attempts to compare the three kallikreins gave inconsistent results which may be due to presence in the preparations of kallikrein of other enzymes acting on the same substrate. Sheep plasma does not form kinins on contact with glass.