Enzymatic properties of human leukocyte elastase complexed to alpha 2-macroglobulin: increases in amidolytic and fibrinolytic activities on incubation
Nagamatsu, Y.; Okamoto, U.; Tsuda, Y.; Okada, Y.; Amemiya, T.
Nihon Ketsueki Gakkai Zasshi Journal of Japan Haematological Society 50(1): 148-157
1987
ISSN/ISBN: 0001-5806 PMID: 2438891 Document Number: 302314
.alpha.2-Macroglobulin and leukocyte elastase-like proteinase (ELP) were partially purified from human blood, and the enzymatic properties of the elastase complexed with .alpha.2-macroglobulin were studied in comparision with those of ELP. The amidolytic activity of the complex was inhibited by Boc-Ala-Tyr-Leu-Val-CH2Cl and di-isopropylphosphofluoridate (DFP), but it was barely inhibited by elastatinal, various trypsin inhibitors and human plasma. The amidolytic activity of the complex immediately after preparation was unaffected by the concentration of sodium perchlorate (NaCIO4), in contrast to that of the complex after incubation for over 24 hr or non-complexed ELP. The fibrinolytic activity of the complex was increased at higher NaCIO4 concentrations, like that of ELP. The molecular weight of the complex showing amidolytic activity after incubation for 24 h at 37.degree. C was approximately 30,000. The amidolytic activity of ELP that was added to .alpha.1-antitrypsin deficient plasma was several times higher than that when added to normal plasma, in contrast to the activity of porcine pancreatic elastase added to both kinds of plasma. These observations suggest that when a part of the ELP released into the blood binds to .alpha.2-macroglobulin, the complex changes gradually to lower molecular weight forms possessing proteolytic activity, which may play an important role in the degradation of proteins under certain circumstances, such as .alpha.-antitrypsin deficient blood or in tissues with little inhibitor.