Table 4.

Inhibitory Activities of Wild-Type and Mutant Recombinant Pre-Elafin Proteins

Pre-Elafin Protein	IC50 (50 nM HNE)
WT pre-elafin	5,634 ± 2,571
MT pre-elafin (T34P)	7,785 ± 1,329

Definition of abbreviations: HNE, human neutrophil elastase; IC₅₀, half-maximal inhibitory concentration; MT, mutant; WT, wild-type.

The inhibitory activities of both proteins were compared by preincubating 50 nM HNE in duplicate with or without 50 pM–100 nM WT or MT pre-elafin for 1 hour at 37°C. Residual HNE activity was quantified using a fluorogenic substrate that is specific for HNE and fluorimetry. Dose–response curves were constructed and IC₅₀ of each inhibitor was determined. IC₅₀ values are represented as means (±SD) (n = 3 separate experiments). The IC₅₀ values for WT versus MT pre-elafin were not significantly different.