Engineered Substrate for Cyclooxygenase-2: A Pentapeptide Isoconformational to Arachidonic Acid for Managing Inflammation

Beyond the conventional mode of working
of anti-inflammatory agents through enzyme inhibition, herein, COX-2
was provided with an alternate substrate. A proline-centered pentapeptide
isoconformational to arachidonic acid, which exhibited appreciable
selectivity for COX-2, overcoming acetic acid- and formalin-induced
pain in rats to almost 80%, was treated as a substrate by the enzyme.
Remarkably, COX-2 metabolized the pentapeptide into small fragments
consisting mainly of di- and tripeptides that ensured the safe breakdown
of the peptide under in vivo conditions. The kinetic parameter Kcat/Km for COX-2-mediated
metabolism of the peptide (6.3 × 105 M–1 s–1) was quite similar to 9.5 × 105 M–1 s–1 for arachidonic acid.
Evidenced by the molecular dynamic studies and the use of Y385F COX-2,
it was observed that the breakage of the pentapeptide has probably
been taken place through H-bond activation of the peptide bond by
the side chains of Y385 and S530.