HIGHLY POTENT IRREVERSIBLE INHIBITORS OF NEUTROPHIL ELASTASE GENERATED BY SELECTION FROM A RANDOMIZED DNA-VALINE PHOSPHONATE LIBRARY

We incorporated a phosphonate irreversible inhibitor of neutrophil ela stase into a randomized DNA library and, using the SELEX process, iter atively selected these assemblies for the most potent elastase inhibit ors. The inhibitors were selected against purified elastase and agains t secreted elastase in the presence of activated neutrophils. Very act ive aptamer inhibitors were obtained by both methods, with second-orde r rate constants for inactivation of human neutrophil elastase ranging (1-3) x 10(8) M(-1) min(-1). These rates exceed those of any reported irreversible inhibitor of elastase and exceed the previous best phosp honate inhibitors by 80-fold. The selected inhibitors are also signifi cantly more potent than alpha-1 proteinase inhibitor in blocking degra dation of elastin by activated neutrophils. In contrast to a previous experiment [Smith et al. (1995) Chem. Biol. 2, 741-750], a single-enan tiomer form of the valyl phosphonate was used rather than a racemic mi xture. Our analysis shows that this use of a chirally resolved valyl p hosphonate results in selection of much more potent inhibitors and tha t these inhibitors specifically potentiate a single enantiomeric form of the phosphonate.