ISSN:
1432-1912
Keywords:
Kinin Conversion
;
Bradykinin
;
Kallidin
;
Arylaminopeptidases
;
Liver
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary A 0.9% sodium chloride homogenate, prepared from healthy human liver tissue collected 12 h following accidental death, was sedimented between 1 500 and 50 000×g. The arylaminopeptidase activity on l-lysyl-, l-arginyl-, l-methionyl- and l-leucyl-β-naphthylamides contained in the pellet was solubilized in 2% sodium desoxycholate. It was, then partially purified by continuous Sephadex gel electrophoresis. Its specific activity on lysyl- and leucyl-β-naphthylamides increased respectively 168- and 340-fold. The enzyme preparation, which seemed to have only one arylaminopeptidase, was shown to convert kallidin (lysylbradykinin, LBK) or methionyllysylbradykinin (MLBK) to bradykinin (BK). Its kininconverting activity was determined by a quantitative method, which is based on incubation with excess substrates (LBK or MLBK), separation of BK formed from excess substrate on columns of carboxymethylcellulose, and assay of BK on the isolated guinea pig ileum. The liver arylaminopeptidase preparation had a kinin-converting activity 5.7 (for LBK) and 6.9 (for MLBK) higher than the respective kinin-converting activities of a 900-fold purified human serum kininconverting enzyme (Guimarães et al., 1973). Evidences derived from a) measurements of initial hydrolysis rates on six l-aminoacyl-β-naphthylamides, and on LBK, MLBK and Leu-Gly-Gly, b) molecular weight estimation, c) microelectrophoretic migration on agarose gel, and d) effect of some inhibitors and ions on the liver arylamidase enzyme, are compatible with the conclusion that the liver and serum kinin-converting enzymes are very similar if not identical. The purest liver enzyme preparation was free of kininase activity.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00499435
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