Abstract
The enzyme cyclo-oxygenase catalyses the oxygenation of arachidonic acid, leading to the formation of prostaglandins. Recently two forms of cyclo-oxygenase have been described: a constitutive (COX-1) enzyme present in most cells and tissues, and an inducible (COX-2) isoenzyme observed in many cells in response to pro-inflammatory cytokines. Constitutive and inducible forms of human cyclo-oxygenase (hCOX-1 and hCOX-2) were cloned and expressed in insect cells, utilizing a baculovirus expression system. hCOX-1 had a specific activity of 18.8 μmol of O2/mg with a K(m) of 13.8 μM for arachidonate and V(max.) of 1500 nmol of O2/nmol of enzyme, whereas hCOX-2 had a specific activity of 12.2 μmol of O2/mg with a K(m) of 8.7 μM for arachidonate and a V(max.) of 1090 nmol of O2/nmol of enzyme. Indomethacin inhibited both hCOX-1 and hCOX-2, whereas NS-398 and Dup-697 selectively inhibited hCOX-2. Both NS-398 and Dup-697 exhibited time-dependent inactivation of hCOX-2, as did indomethacin on both enzymes. The competitive inhibitor of hCOX-1, mefenamic acid, also displayed competitive inhibition of hCOX-2. These results demonstrate the ability to generate selective non-steroidal anti-inflammatory drugs (NSAIDs), which could provide useful improvement therapeutically in the treatment of chronic inflammatory disease.
Original language | English |
---|---|
Pages (from-to) | 479-484 |
Number of pages | 6 |
Journal | Biochemical Journal |
Volume | 305 |
Issue number | 2 |
DOIs | |
State | Published - 1995 |