Brain Peptidases: Conversion and Inactivation of Kinin Hormones

Abstract

Abstract— Two enzymes that selectively hydrolyse kinins at pH 7.5 were obtained in partially purified form from the supernatant fraction of homogenates of previously frozen rabbit brain by gel filtration on Sephadex G‐100. The enzymes were detected and their activity estimated by bioassay with the isolated guinea pig ileum The products of the enzymic reactions were identified by high voltage electrophoresis at pH 3.5 and by the determination with the amino acid analyser of the amino acids released from the kinins. One enzyme, kinin‐converting enzyme, catalyses the hydrolysis of kinin‐10 (Lysbradykinin) and kinin‐11 (Met‐Lys‐bradykinin) into kinin‐9 (bradykinin). It also hydrolyses the aminoacyl‐8‐naphthylamides of methionine, lysine, arginine and leucine. The conversion of kinin‐10 to kinin‐9 was inhibited by puromycin (Ki 3.5 × 10−5 M) These properties are similar to those of brain arylamidases described in the literature. Kininase, the second enzyme, inactives kinins 9, 10 and 11 by peptide‐bond hydrolysis. Similar rates of release of arginine and phenylalanine were observed for the three kinins, suggesting that kininase acts at the carboxy‐terminus of these peptides. Our results suggest that brain contains proteases which apparently selectively metabolize polypeptide hormones that exert definite pharmacological effects on the central and peripheral nervous systems.

Antinociceptive action of bradykinin and related kinins of larger molecular weights by the intraventricular route

“…had a delayed onset of action, which was evident with L-Bk and increased to a maximal effect with ML-Bk and GAML-Bk. The return to normal, however, followed a similar time-course, which may indicate that the larger kinins act as such and not because of their eventual transformation into Bk; such a transformation is possible for enzymes have been detected in the brain tissue that can release Bk from L-Bk (Camargo, Ramalho Pinto & Greene, 1972).…”

Development of Highly Potent and Selective Phosphinic Peptide Inhibitors of Zinc Endopeptidase 24-15 Using Combinatorial Chemistry

“…In this respect, it can be mentioned that the best specificity constant (k cat /K m ratio) for rat 24-15 has been observed for the hydrolysis of dynorphin A [1][2][3][4][5][6][7][8] (3,9). In this peptide (Tyr Among other factors that may influence the specificity of 24-15, the presence of a free C-terminal carboxylate group has been previously pointed out (28,30).…”

“…The protection of the hydroxyphosphinyl group by the adamantyl group will be published elsewhere. 2 The…”

“…The endopeptidase 1 belongs to the zinc metalloprotease family (1) and resembles a peptidase previously purified from rabbit brain by Camargo et al (2). Later, endopeptidase 24-15 was named thimet oligopeptidase with respect to the thiol and metal dependence of its catalytic activity (3)(4)(5).…”

SP-Sephadex equilibrium chromatography of bradykinin and related peptides: Application to trypsin-treated human plasma

“…also Ref. (19) which indicates that reported electrophoretic separations were not reproduced), high-voltage paper electrophoresis (pyridineacetic acid buffer) (20); gel filtration on Sephadex 0-15 (21), and gradient elution chromatography on CM-cellulose (22) or CM-Sephadex (23). An excellent review and analysis of the chromatographie approaches to the problem of extracting, desalting, and separating kinins is given in Ref.…”