Abstract
1. Applying the method of ROCHA E SILVA for purification of bradykinin, partial purification of the active substance in ZETLER'S Fa-fraction from the crude brain SP has been attempted.
2. The active substance was concentrated to about 50 times as active as the crude preparation, the partially purified active polypeptide was found to be quite similar to bradykinin in the pharmacological and chemical properties.
3. Brain homogenates of rabbits have been investigated for the presence of kinin-forming and-destroying activities.
4. Kinin-forming activity was chiefly detected in the microsomal fraction and it appears to be attributable to the presence of a kallikrein-like enzyme or enzymes.
5. Kininase activity was present in all the subcellular fractions of rabbit brain, the highest in the soluble fraction. But considerable activity was firmly bound with cytoplasmic granules and appears not to originate from intracellular cathepsins.
