All are examples of competitive enzyme blockage except: (A) Cyclooxygenase by Aspirin, (B) Thymidylate synthase by 5-FU, (C) Coagulation by Dicumarol, (D) DHFR by Methotrexate
Answer is A. Kinetics of enzyme inhibition Competitive inhibitionNon competitive inhibitionKm Increased No change V max No change Decreased Significance Drug action Toxicological (Refer: Harper's Illustrated Biochemistry, 26th edition, pg no: 67-68)