Conductimetry: a new tool for studying inhibition of elastolysis

The conductimetric method was applied to the measurement of human leukocyte elastase activity, using insoluble elastin as a substrate. From conductance changes, initial rates of elastolysis were derived. A linear relationship of enzyme activity with enzyme concentration was demonstrated up to 400nM of enzyme, for three different substrates. In this concentration range, inhibition of elastolysis by eglin c was studied for different concentrations of eglin c. A 50% inhibitory concentrations of 0.13-0.15 microM of eglin c was derived from our results, corresponding to an inhibitor/enzyme ratio of about 0.5, indicating a strong inhibition, as previously demonstrated by authors using synthetic substrates.