1. Crude preparation of substance P (SP) from the brains of several species and bovine peripheral nerves (ventral and dorsal root, vagus in the neck) were analyzed by alumina column chromatography, paper electrophoresis and paper chromatography, its biological activity being assayed on four different isolated tissues;guinea-pig ileum, chicken rectal caecum, rat uterus and duodenum.
2. The presence in the nerve granules of SP itself and ZETLER'S satellite polypeptides of SP, his Fa- and Fc-peptide, was demonstrated.
3. It was proved that Fa-peptide is quite similar to or identical with bradykinin.
4. ZETLER'S CC1₄ treatment of the crude SP as well as LEMBECK's chloroformmethanol extraction was shown to cause an increase in Fa-peptide content.
5. Fa-peptide could be, as reported by LEMBECK and his co-workers, extracted by chloroform-methanol from the brain tissue, but its solubility in the organic solvent was found to be far less than that in water, about a half being easily transfered to water phase by mere washing, while a greater part of SP itself was left unextracted.Therefore it appears not so likely that SP and Fa-peptide bind with lipids in the nervous tissues.
6. When partially purified SP prepared from nerve granules by alumina column chromatography was incubated with trypsin, plasmin or kallikrein, SP itself was inactivated but a kinin-like component nearly identical with Fa-peptide was newly formed.A precursor or precursors in nerve granules of such a kinin-like substance were shown to be easily released with SP itself by laking the granules in neutral hypotonic solutions.
7. Leaving aside the question as to whether or not it is naturally-occurring, therefore, Fa-peptide pre-existing in the neuronal SP preparation can probably be considered to be formed by a kinin forming enzyme or enzymes and protein denaturation.