Abstract
Separation of kininases from the rat brain and identification of the products produced by these enzymes were examined using DEAE-cellulose column chromatography and thin-layer chromatography, respectively. Fraction A (F-A), which was developed with 70 mM NaCl, released Arg-Pro-Pro-Gly-Phe and Ser-Pro-Phe-Arg, fraction B (F-B), with 100 mM NaCl, cleaved the Pro7-Phe8 and Phe8-Arg9 peptide bonds of the bradykinin molecule and fraction C (F-C) with 150 mM NaCl hydrolyzed bradykinin to amino acids. The specific activity of each fraction determined by the bioassay system was 158.7, 51.0 and 14.8 nmole bradykinin/mg protein/ min, respectively. The intensities of their fluorescence on the chromatogram showed visibly that o-phenanthroline effectively inhibited F-A, B and C at a concentration of 0.5 mM. These results suggest that heterogeneous enzyme systems are present in the rat brain and regulate the levels of bradykinin in the brain.
