Isolation and partial characterization of a proteinase with elastolytic activity from mouse blood leukocytes

Leukocyte elastase has been implicated in the etiology of pulmonary emphysema. Recently, two genetic models of emphysema have been described, in mouse, which may enhance our understanding of the pathogenesis of emphysema. We therefore sought to purify mouse leukocyte elastase in order to characterize its biochemical properties. Leukocyte enzyme has been purified by a two-step procedure involving salt extraction of granular fraction, followed by preparative isoelectric focusing on Sephadex G-75 Superfine. The enzyme hydrolyses elastin and synthetic substrates for elastase, even if to a different extent. Inhibition studies indicates that the enzyme is a serine proteinase. Mouse elastase has a single isoelectric point of 8.65 and it behaves on sodium dodecyl sulphate polyacrylamide gel electrophoresis as a major band (molecular weight 29,000) and two minor bands (molecular weight 27,000 and 25,800, respectively.