[Detection of human leukocyte elastase from a plasma alpha-1-proteinase inhibitor complex by its enzymatic activity...

A spectrophotometric procedure was developed for estimation of elastase activity in human leukocytes in the form of complex with blood serum alpha 1 proteinase inhibitor after loosening of the complex and detection of the enzymatic activity with N-tert-butyl-hydroxy-carbonyl-Ala-p-nitrophenyl ester as a substrate in presence of acetone or acetonitrile. The optimal conditions were described, which were required for estimation of the enzyme 100% activity followed by addition of the leukocyte elastase standard preparation into blood serum as well as for measurement of the enzyme activity in the complex with alpha 1 proteinase inhibitor. The procedure took 6-10 min to evaluate the elastase activity in the complex with the inhibitor using simple buffer containing organic solvents at 30 degrees and the available two-beam spectrophotometer.