The distribution and properties of neutral peptidases acting on the peptide hormone bradykinin (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg) were determined in several rabbit tissues. The supernatant and particulate fractions prepared from tissue homogenates (25000g for 60min) were studied. Bradykinin inactivation (kininase activity) was measured by bioassay with the isolated guinea-pig ileum. The sites of peptide-bond cleavage were determined in the amino acid analyser, which permits detection and measurement of amino acids and peptides derived from bradykinin. The results indicate that kininases are present in a wide range of concentrations in different tissues, kidney and lung having the most activity. Kininases present in different tissues were distinguished on the basis of sensitivity to the effects of EDTA, dithiothreitol and ZnCl2 and by the site of peptide-bond hydrolysis in bradykinin.
A Synopsis of Kinin '75 -Abstracts bradykinin. Glands of 21 (15+6) days old rats showed a kallikrein concentration higher than those found'in the control. In the 60 days old rats IPR caused a decrease in the kallikrein of the gland. This is probably due to an unespecific increase of all proteins. The kallikrein activity after IPR was followed in the 90 days old rats. The greater concentration ot kallikrein was found at 6 hr after the drug. The decrease verified at 2 hr may be explained by an increase of saliva secretion evoked by IPR. The blockade of the IPR effect produced by actinomycin demonstrates that kallikrein is synthetized by the gland. As the drug stimulates the acini development it is suggested that these extructures are associated with the production of kallikrein.(*) CNICT, ARGENTINA. BRADYKININ INACTIVATING ENZYMES IN RABBIT TISSUES: SITES OF PEPTIDE BOND HYDROLYSIS MARIA CICILINI, JANE D. BERTI and A. C. M. CAMARGO Dept. of Pharmacology and Protein Chemistry Laboratory, Faculty of Medicine, Ribeirao Preto, Sao Paulo, Brazil.A comparative study of the distribution of Kininase activity in rabbit tissuses was carried out using the isolated guinea pig ileum biossay to determine total activity at pH 7.5 and ion exchange chromatography to identify the major peptides derived from bradykinin (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg). The supernatant and sedimentable fractions prepared by centrifugation (25,000xgxl hr) from 0.25 M sucrose homogenates of each tissue were -studied separately. The relative order of specific activity (#g bradykinin inactivated min -1, mg protein ~ ) found is kidney, lung, heart, spleen, brain, skin, skeletal muscle, liver plasma and smooth muscle, with kidney being approximately 25 times higler than smooth muscle. The major peptide fragments and free amino acids produced by 50 % hydrolysis of 80#M bradykinin in 0.05 M sodium phosphate buffer, pH 7.5 at 37 ~ , were determined with an amino acid analyzer using Aminex A-5 and Aminex A-6 resins and ninhydrin for detection. Although the spectrum of products produced by the tissues were similar, both qualitative and quantitative differences were observed. The data indicate that bradykinin is inactivated by the action of endo-and/for exopeptidases acting primarily on the ProT-Phe 8 peptide bond with some hydrilysis of the Phe5-Ser 6 bond. Although these results on homogenates cannot be directly applied to the question of the physiological inactivation of bradykinin in situ, they do indicate the similarity of peptidase activities in the large number of tissues examined.
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