Kinetics of the inhibition of free and elastin-bound human pancreatic elastase by alpha 1-proteinase inhibitor and alpha 2-macroglobulin.
At pH 8.0 and 25 degrees C alpha 1-proteinase inhibitor and alpha 2-macroglobulin bind human pancreatic elastase with rate constants of 4.7.10(5) M-1.s-1 and 6.4.10(6) M-1.s-1, respectively. The corresponding delay times of elastase inhibition in plasma are 0.4 s and 0.2 s, respectively, indicating that both inhibitors may act as physiological antielastases. Elastin impairs the elastase inhibitory capacity of alpha 1-proteinase inhibitor and alpha 2-macroglobulin. In presence of human elastin, the former behaves like a slow-binding elastase inhibitor, with a rate constant of about 260 M-1.s-1. In contrast, alpha 2-macroglobulin is a fast-binding inhibitor of elastin-bound elastase, but only one of its two sites is functioning in presence of elastin.
Laurent
P
P
Laboratoire d'Enzymologie, INSERM Unité 237, Université Louis Pasteur de Strasbourg, Illkirch, France.
Bieth
J G
JG
D000818:Animals; D001667:Binding, Competitive; D001798:Blood Proteins / Q000494:pharmacology*; D004549:Elastin / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D010179:Pancreas / Q000201:enzymology*; D010196:Pancreatic Elastase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011480:Protease Inhibitors; D013552:Swine; D000515:alpha 1-Antitrypsin; D000511:alpha-Macroglobulins / Q000494:pharmacology*
D001798:Blood Proteins; D011480:Protease Inhibitors; D000515:alpha 1-Antitrypsin; D000511:alpha-Macroglobulins; D004549:Elastin; D010196:Pancreatic Elastase