Sensitive substrates for neprilysin (neutral endopeptidase) and thermolysin that are highly resistant to serine proteases

Publisher Website
Google Scholar
Abstract
Tripeptide derivatives like 3-carboxypropanoylalanyl-alanyl-leucine 4-nitroanilide or 3-carboxypropanoylalanyl-alanyl-phenylalanine 4-nitroanilide are very sensitive substrates for neprilysin (k cat > 102 s−1; k cat/K m ≥ 106 s−1 · M−1) and are widely employed in investigations of the enzyme. However, these compounds are also good substrates for the serine proteases chymotrypsin and subtilisin (k cat ∼ 1s−34 s−1). By substituting the N-terminal alanine of the substrates with proline, the catalytic efficiency of the enzymic reaction, by the serine proteases, is diminished by 2–3 orders of magnitude, whereas that by neprilysin and thermolysin decreases only slightly. These effects demonstrate that structural alterations in peptide substrates that impair secondary sub-site interactions with one class of peptidases may enhance the selectivity of the substrates towards another class of peptidases.