Fast Solubilization of Human Lung Elastin byPseudomonas aeruginosaElastase1,2

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Abstract
Pseudomonas aeruginosa may cause severe lung infections in humans. This bacteria secretes an elastase that might degrade lung elastin. We have studied the solubilization of human lung elastin by P. aeruginosa elastase in an attempt to delineate the pathogenic role of this proteinase in P. aeruginosa lung infections. We also used bovine ligamentum nuchae elastin and human leukocyte elastase for comparative purposes. With an elastin concentration of 5 mg·ml−1 and at physiologic ionic strength, P. aeruginosa elastase is about 50 times more active on human lung elastin than on bovine elastin. In contrast, human leukocyte elastase has similar specific activities on the 2 substrates. In addition, the bacterial enzyme is about 10 times more active on human elastin than the neutrophil elastase but the latter is about 5 times more active on bovine elastin than the former. In order to better quantitate these enzyme-substrate interactions, we have measured initial rates of elastolysis, derived from product versus ti...