PURIFICATION AND PROPERTIES OF A SUBSTANCE P-INACTIVATING ENZYME FROM BOVINE BRAIN

An enzyme which inactivates Substance P at neutral pH has been extracted and purified from bovine brain. The action of the purified kininase on SP shows a broad pH optimum near 6·4, while proteinase action of the preparation toward hemoglobin is maximal near 4·0. Physical and enzymatic properties of the kininase differ from those of known brain enzymes. The smooth muscle activities of bradykinin and kallidin are also destroyed upon incubation with the enzyme, but eledoisin is unaffected. The significance of the reported enzyme is discussed in terms of a possible neurohumoral activity of Substance P in the central nervous system. © 1968.