Aspirin inhibits platelet function by acetylating :
a) prostaglandin reductase
b) thromboxane synthetase
c) cyclooxygenase
d) succinic dehydrogenase
e) NADH-cytochrome-c-reductase
Answer:
c) cyclooxygenase
Explanation
Aspirin inhibits platelet function by permanently acetylating the cyclooxygenase that forms prostaglandins
Aspirin suppresses the production of both prostaglandins and thromboxanes. This happens because cyclooxygenase, an enzyme that participates in the production of prostaglandins and thromboxanes, is irreversibly inhibited when aspirin acetylates it. This makes aspirin different from other NSAIDS (such as diclofenac and ibuprofen), which are reversible inhibitors.
More recent work has shown that there are at least two different types of cyclooxygenase: COX-1 and COX-2. Aspirin inhibits both of them. Newer NSAID drugs called COX-2 selective inhibitors have been developed that inhibit only COX-2, with the hope for reduction of gastrointestinal side-effects.