title: Determination of elastase inhibitory activity of alpha 1-proteinase inhibitor and bronchial antileukoprotease: different results using insoluble elastin or synthetic low molecular weight substrates.
abstract: We have determined the effect of two elastase-specific synthetic low molecular weight substrates, L-pyroglutamylprolylvaline-paranitroanilide and succinyltrialanyl-paranitroanilide, together with insoluble elastin-fluorescein, on the determination of the neutrophil elastase (NE) inhibitory capacity of purified alpha 1-proteinase inhibitor (alpha 1-PI) and bronchial antileukoprotease (ALP). In addition, the inhibitory capacities of mixtures of alpha 1-proteinase inhibitor, antileukoprotease and alpha 2-macroglobulin prepared in ratios similar to that in lung secretions were determined. Purified inhibitors, alone or in combinations, inhibited about 1 mole neutrophil elastase per mole inhibitor when assessed using synthetic substrates. However, when elastin-fluorescein was used in the assay system, the purified inhibitors showed an inhibitory capacity that was 40-85% of the value obtained using synthetic substrates. Even less inhibition was observed when mixtures of inhibitors were assessed using elastin-fluorescein (23-44% of the value for synthetic substrates). Our data indicate that results of elastase inhibitor activity measurements depend on the type of substrate which has been used.
mesh_terms: D001798:Blood Proteins / Q000494:pharmacology*; D001980:Bronchi / Q000201:enzymology*; D001991:Bronchitis / Q000201:enzymology; D002908:Chronic Disease; D004549:Elastin / Q000494:pharmacology*; D006801:Humans; D008970:Molecular Weight; D009504:Neutrophils / Q000201:enzymology*; D009842:Oligopeptides / Q000494:pharmacology*; D010196:Pancreatic Elastase / Q000378:metabolism*; D011480:Protease Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D000515:alpha 1-Antitrypsin; D000511:alpha-Macroglobulins / Q000494:pharmacology
chemical_list: D001798:Blood Proteins; D009842:Oligopeptides; D011480:Protease Inhibitors; D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins; D000515:alpha 1-Antitrypsin; D000511:alpha-Macroglobulins; C015516:succinyl-trialanine-4-nitroanilide; C039741:S 2484; D004549:Elastin; D010196:Pancreatic Elastase; D011761:Pyrrolidonecarboxylic Acid