title: On the inhibition of elastase by serum. Some distinguishing properties of alpha1-antitrypsin and alpha2-macroglobulin.
abstract: 1. The influence of serum on the elastolytic and esterolytic activity of elastase has been studied. With both substrates the inhibition curves are linear. 1 ml of normal human serum inhibits the activity of 0.77 mg of pure porcine elastase. 2. Elastase binds faster with alpha2-macroglobulin (k = 3.4-10(6) M-1 S-1) than it does with alpha1-antitrypsin (k = 5-10(5) M-1 S-1). 3. The dissociation constant of the alpha-antitrypsin -elastase complex is much lower than that of the alpha2-macroglobulin-elastase complex but both complexes are very stable (Ki less than 10(-10) M). 4. Protein pi (inter-alpha-inhibitor) does not inhibit elastase.
mesh_terms: D000818:Animals; D001665:Binding Sites; D001798:Blood Proteins / Q000494:pharmacology; D002850:Chromatography, Gel; D006801:Humans; D007700:Kinetics; D008259:Macroglobulins / Q000494:pharmacology*; D008433:Mathematics; D010179:Pancreas / Q000201:enzymology; D010196:Pancreatic Elastase / Q000037:antagonists & inhibitors*; D011485:Protein Binding; D013552:Swine; D000515:alpha 1-Antitrypsin / Q000494:pharmacology*
chemical_list: D001798:Blood Proteins; D008259:Macroglobulins; D000515:alpha 1-Antitrypsin; D010196:Pancreatic Elastase