Isolation and characterization of porcine leukocyte elastase. Leukocyte elastase-inhibitor complexes in porcine...

Porcine leukocyte elastase was purified from granulocytes by chelating chromatography on copper chelate Sepharose and by ion exchange chromatography on CM-Sepharose. Thus an enzyme preparation with a specific activity (substrate: MeOSuc(Ala)2ProValNan) of 89.3 U/mg protein was obtained. Dodecyl sulphate gel electrophoresis revealed one protein band corresponding to a molecular mass of 27 kDa. The amino acid composition was determined and isoleucine was identified as the only N-terminal amino acid residue. The bimolecular velocity constant for the inhibition by diisopropyl fluorophosphate was determined as 2000 1 . mol-1 . min-1. The dissociation constants, Ki, of the complexes of porcine leukocyte elastase with various inhibitors were calculated. The kinetic constants for the elastase-catalysed hydrolysis of MeOSuc(Ala)2ProValNan, Suc(Ala)2ValNan and Suc(Ala)3Nan were determined, as well as the kinetic constants of the inactivation of leukocyte elastase by active site mapping reagents. Detergents such as Triton X-100, Tween 20 and Brij 35, as well as porcine serum albumin, activated the porcine leukocyte elastase preparation.